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1.
The effect of trypsin on vascular tone and the cytosolic calcium concentration ([Ca(2+)](i)) of endothelial and smooth muscle cells were examined in the rat aorta. A calcium indicator, fura-PE3, was used to measure [Ca(2+)](i) simultaneously with vascular tone. In the endothelium-intact rat aorta, carbachol and trypsin increased [Ca(2+)](i) in a dose-dependent manner. In the endothelium-denuded rat aorta, carbachol did not change [Ca(2+)](i), but trypsin slightly increased it. Addition of trypsin to the norepinephrine-stimulated rat aorta relaxed the muscle with an additional increase in [Ca(2+)](i). Under calcium-free conditions, trypsin induced a transient increase in [Ca(2+)](i). Trypsin-induced endothelium-dependent relaxation was inhibited by preincubation with l-NMMA, an endothelial NO synthase inhibitor, U-73122, a phospholipase C inhibitor, cyclopiazonic acid, a sarcoplasmic/endoplasmic reticulum Ca(2+)-ATPase blocker, and lanthanum, a nonselective Ca(2+) channel blocker. However, indomethacin, a nonselective cyclooxygenase inhibitor, and SKF-96365, a store-operated Ca(2+)-channel blocker, had no effect on the trypsin-induced relaxation. These results suggest that trypsin increases [Ca(2+)](i) in the endothelial cells through SKF-96365-insensitive Ca(2+) channels and regulates the release of NO, which results in relaxation of the rat aorta.  相似文献   

2.
The role of rhoA/rho-associated kinase (ROK) signaling pathways in agonist-induced contraction of the rat myometrium was investigated. We measured the [Ca(2+)](i)-force relationship, phosphorylation of myosin regulatory light chains (MLC(20)) in intact tissue and the Ca(2+)-sensitization of force in permeabilized myometrial cells of rat. In measurements of the relationship between [Ca(2+)](i) and tension in intact tissue, Y-27632, a ROK inhibitor, significantly attenuated the carbachol-induced contraction without changing [Ca (2+)](i). Phosphorylation of MLC(20) was increased by carbachol and this increased phosphorylation was blocked by treatment of tissue with Y-27632. In tension measurements of single hyperpermeable cells, carbachol evoked sustained contraction at constant pCa 6.7 and these agonist-induced contractions were decreased by treatment with Y-27632. These results suggest that activation of a ROK-mediated signaling pathway(s) plays an important role in agonist-induced alterations in MLC(20) phosphorylation and force of rat myometrium.  相似文献   

3.
Li L  Li X  Yan J 《Veterinary parasitology》2008,157(1-2):21-33
Toxoplasma gondii (T. gondii) invasion of host cells is a complicated process of interaction between parasites and host cells. In the present study we investigated the alterations of free Ca(2+) concentration ([Ca(2+)](i)) and cytoskeletons in phagocytic and non-phagocytic host cells and arachidonic acid (AA) concentration in cells supernatant during T. gondii invasion. T. gondii invasion induced significant elevation of intracellular [Ca(2+)](i) in phagocytic cells (J774A.1) but not in non-phagocytic cells (L929). Pre-treatment of J774A.1 cells with Phospholipase C (PLC) inhibitor (U73122), or Ca(2+) chelators (EGTA, BAPTA/AM) did not block elevations of [Ca(2+)](i) but the elevations were lower and of shorter duration than that in untreated cells. Pre-treatment of tachyzoites with Phospholipases A (PLA) inhibitors (4-BPB and AACOCF3) resulted in a similar pattern of increasing of [Ca(2+)](i) as that in Ca(2+) chelators treated cells. Agglutinations of microfilaments were observed in J774A.1 cells but not in L929 cells. No changes of microtubules were observed in either cell. Treatment of cells with cytoskeleton inhibitors (colchicines, cytochalasin-D) resulted in reduced cell infection ratios. AA concentration in J774A.1 cells supernatant reached 8.44-fold of basal concentration after T. gondii infection and those in 4-BPB or AACOCF3 pre-treated cells reached 7.70-fold and 8.09-fold of basal concentration, respectively. However, elevation of AA concentrations induced by 4-BPB or AACOCF3 treated tachyzoites were 3.02-fold and 2.65-fold of basal AA concentration. AA concentration in L929 cells supernatant reached 5.02-fold of basal concentration after T. gondii infection and those in 4-BPB or AACOCF3 pre-treated cells reached 4.75-fold and 4.78-fold of basal concentration, respectively. However, elevation of AA concentrations induced by 4-BPB or AACOCF3 treated tachyzoites were 2.06-fold and 2.43-fold of basal AA concentration. Results indicated that elevations of [Ca(2+)](i) and AA induced by T. gondii invasion were from both host cells and parasites. T. gondii invasion activated host cell PLC and triggered the PLC-PKC signal pathway, which resulted in the flowing of extracellular Ca(2+) and the releasing of intracellular Ca(2+) pool. Elevated [Ca(2+)](i) induced reorganization of host cell microfilaments. The invasion also activated secretory PLA(2) (sPLA(2)) and cytosolic PLA(2) (cPLA(2)) of the parasite to release AA, which increased the permeability of cell membrane.  相似文献   

4.
Seventeen cows divided into 3 groups were studied: Group 1 consisting of newly delivered cows (1–3 days post partum) suffering from parturient paresis; Group 2 comprising newly delivered (1–4 days post parturn) healthy cows and Group 3 consisting of non-pregnant, non-lactating cattle. All animals were given an intravenous standard Ca infusion, and blood samples were obtained before treatment and at intervals during a 3-hour period thereafter. Plasma levels of calcitonin (CT), calcium (Ca) and inorg. phosphate (P) were determined. No significant difference for the mean CT response existed between animals in Groups 1 and 2. Blood levels of inorg. P increased significantly with time in animals of Groups 1 and 2 but not in animals of Group 3.The finding here of a similar CT response after Ca stimulation in both paretic and non-paretic cows demonstrates that the C-cells in both groups of animals have the same capacity to secrete CT.  相似文献   

5.
The blood levels of calcium, inorganic phosphorus, magnesium, glucose and NEFA were studied in cows at the time around partus. Eight of 16 cows developed hypocalcaemic paresis. Besides hypocalcaemia the paretic cows showed lower levels of inorganic phosphorus and higher levels of glucose and NEFA than non-paretic cows 24 hrs. post partum. It is known that lipolysis is associated with uptake of calcium in adipose tissue. The calcium content in perirenal adipose tissue was however lower in paretic cows than in non-paretic parturient cows and lactating cows slaughtered 3–5 months after calving. The calcium content in omental adipose tissue was about the same in all 3 groups. Despite increased lipolysis the calcium content in adipose tissue is thus not increased in cows suffering from parturient paresis.  相似文献   

6.
A study was conducted to examine sources of variation introduced into a phagocytosis assay as a result of the isolation of neutrophils from bovine blood, including variation attributable to isolation of neutrophils from blood, variation between duplicate determinations of percentage phagocytosis, and the variation in the ability of neutrophils isolated from blood (over repeated collections from the jugular vein) to phagocytose. For the phagocytosis assay, jugular venous blood from each of 4 cows was divided into 2 equal portions. The neutrophils were isolated by lysis of red blood cells with 0.2% sodium chloride. The neutrophils (2 x 10(7)) were incubated in duplicate with 32P-labeled Staphylococcus aureus ([32P]SA; 2 x 10(8)) in skimmed milk samples (2.5% final concentration) prepared from 4 cows. This process was repeated thrice on neutrophils isolated from 4 cows at 2-week intervals. The proportions of variation in percentage of 32P-labeled S aureus phagocytosed between duplicate neutrophil isolations and between duplicate assay determinations were 0 and 1%. Differences among skimmed milk sources and among runs, using blood neutrophils taken at different times from the same donor cow, accounted for 62 and 36% of the total variation. The results indicated that variation arising from blood neutrophil isolation introduced into a phagocytosis assay within a single-day trial is of no concern. The large variation among skimmed milk sample sources indicated differences among cows in the ability of their milk to support phagocytosis. The variation in neutrophil isolations over time for any cow was considered too large to allow for evaluation of physiologic and environmental effects on phagocytosis of neutrophils isolated from blood.  相似文献   

7.
REASONS FOR PERFORMING STUDY: Ca2+ homeostasis in articular chondrocytes affects synthesis and degradation of the cartilage matrix, as well as other cellular functions, thereby contributing to joint integrity. Although it will be affected by mechanical loading, the sensitivity of intracellular Ca2+ concentration ([Ca2+]i) in equine articular chondrocytes to many stimuli remains unknown. HYPOTHESIS: An improved understanding of Ca2+ homeostasis in equine articular chondrocytes, and how it is altered during joint loading and pathology, will be important in understanding how joints respond to mechanical loads. METHODS: [Ca2+]i was determined using the fluorophore fura-2. We examined the effects of hypotonic shock, a perturbation experienced in vivo during mechanical loading cycles. We used inhibitors of Ca2+ transporters to ascertain the important factors in Ca2+ homeostasis. RESULTS: Under isotonic conditions, [Ca2+]i was 148 +/- 23 nmol/l, increasing by 216 +/- 66 nmol/l in response to reduction in extracellular osmolality of 50%. Resting [Ca2+]i, and the increase following hypotonic shock, were decreased by Ca2+ removal; they were both elevated when extracellular [Ca2+] ([Ca2+]o) was raised or following Na+ removal. The hypotonicity-induced rise in [Ca2+]i was inhibited by exposure of cells to gadolinium (Gd3+; 10 micromol/l), an inhibitor of mechanosensitive channels. [Ca2+]i was also elevated following treatment of cells with thapsigargin (10 micromol/l), an inhibitor of the Ca2+ pump of intracellular stores. CONCLUSIONS: A model is presented which interprets these findings in relation to Ca2+ homeostasis in equine articular chondrocytes, including the presence of mechanosensitive channels allowing Ca2+ entry, a Na+/Ca2+ exchanger for removal of intracellular Ca2+ and intracellular stores sensitive to thapsigargin. POTENTIAL RELEVANCE: A more complete understanding of Ca2+ homeostasis in equine chondrocytes may allow development of future therapeutic regimes to ameliorate joint disease.  相似文献   

8.
The article describes the dynamics of changes in blood concentrations of the active substances present in the solution after its infusion to healthy cows in comparison to NaCI solution as well as the response of paretic cows to treatment with the new complex solution. Cows received a dose of 400 ml of A1 solution (containing 8.4 g of Ca2+) intravenously. In healthy cows the average calcium concentration in blood serum prior to the test was 2.52 +/- 0.08 mmol/l while 15 min. after the infusion the concentration rose to 3.10 +/- 0.08 mmol/l (p < 0.05) and magnesium concentration rose from 0.61 +/- 0.05 to 1.39 +/- 0.08 mmol/l (p < 0.05). This experiment showed that elevated concentration of non-organic phosphates persisted 1 hour after infusion (p < 0.05). In the second phase of efficacy evaluation of the novel preparation A1 on paretic cows the intravenous injection of 1 ml/kg of body weight of A1 solution increased calcium concentration up to almost normal level (p < 0.05). The level of magnesium in serum 1 h after injection was statistically significantly higher by 63% (p < 0.05) and reached the physiologically normal concentration. 1 h after the infusion of test solution the level of phosphate was higher by 13% (p > 0.05). The rise was statistically not significant. Even though A1 solution undoubtedly produced an increase in glucose concentration in the blood serum, due to wide dispersion of individual measurements and high standard deviation the increase (p > 0.05) in glucose concentration was found insignificant. Most of the treated paretic cows rose within 1-6 h after infusion of 400 ml of solution A1. No relapses were observed. A combination of different salts of calcium and magnesium, non-organic phosphates and glucose with analeptic substance mixed in one solution (A1 solution) administered at a dose of 1 ml/kg of body weight raises concentrations of essential macroelements in blood serum of cattle and promotes improvement of paretic cows condition.  相似文献   

9.
The main purpose of this study was to check whether phyto- and endogenous estrogens influence calcium ion mobilization [Ca(2+)](i) in bovine endometrial cells and whether this action is connected with biological effects i.e. prostaglandin (PG)F(2alpha) production. In our study we used two calcium measurement methods by comparing the microscopic method with widely used quantitative - spectrofluorometric method of [Ca(2+)](i) measurement. We also wanted to confirm whether visualization of calcium ion [Ca(2+)](i) in cells using microscopic method supported by micro image analysis (Micro Image Olympus system) reflects real, qualitative changes in the ion concentration. In both methods a cell-permeable form of fluorescent [Ca(2+)](i) indicator Fura-2 was used. Cultured bovine endometrial epithelial and stromal cells influenced by phorbol-2-myristate-13-acetate (PMA; positive control), estradiol 17-beta (E(2); endogenous estrogen) and active metabolites of phytoestrogens (environmental estrogens) were used as a model to study PGF(2alpha) secretion and [Ca(2+)](i) mobilization in the cells. Equol and para-ethyl-phenol in doses of 10(-8)-10(-6) M increased PGF(2alpha) concentration both in epithelial and stromal cells (P<0.05). In both methods, equol and para-ethyl-phenol did not cause intracellular [Ca(2+)](i) mobilization in epithelial and stromal cells (P>0.05). Both methods revealed that only E(2) and PMA induced intracellular [Ca(2+)](i) mobilization in epithelial and stromal cells (P<0.05). The results of both methods were highly correlated (P<0.001; r=0.82 for epithelial cells and r=0.89 for stromal cells). In conclusion, both methods gave approximately the same results and showed that phytoestrogens, in contrast to PMA and E(2), did not cause intracellular [Ca(2+)](i) mobilization in endometrial cells. The obtained results proved that the [Ca(2+)](i) visualization method supported by micro image analysis can produce similar results to the spectrofluorometric method.  相似文献   

10.
To determine the effects of ozone on the phagocytosis of bovine polymorphonuclear leukocytes (PMNs), ozone gas was administered in vitro on the blood and milk of healthy lactating cows, cows with acute mastitis, and cows with milk fever. In the blood of healthy dairy cattle, although there was no significant effect of ozone gas on the viability of the leukocytes, phagocytosis of PMNs significantly decreased. In contrast, ozone gas administration in vitro significantly increased phagocytosis of PMNs from the blood of cows with acute mastitis and milk fever, and from mastitic milk. These findings showed that ozone administration in vitro has positive and negative effects on bovine PMN phagocytosis, depending on the health status of the animal.  相似文献   

11.
A mobile, hand-held ionized calcium and pH analyser, the IRMA (Immediate Response Mobile Analyser) SL (Diametrics Medical Inc. St. Paul, MN, USA), was evaluated and results interpreted with help from data derived on biological variation in five dry cows. The maximum allowable analytical imprecision (CMAX) was estimated as 1.33% for [Ca++] and 0.12% for pH; the maximal allowable analytical inaccuracy (BMAX) was estimated to be 1.82% ([Ca++]) and 0.09% (pH), and the maximum allowable difference between two methods (MAXDIFF) was calculated as 0.89% ([Ca++]) and 0.08% (pH). These values were compared with the coefficient of variation obtained by calculation from analysis results in blood samples obtained from 51 cows, heifers and calves. The between-cow coefficient of variation (CV), within-cow CV, critical difference (two-sided) and index of individuality were estimated as 4.77, 2.66 and 14.29%, and 1.08 for [Ca++] analysis. For pH measurements, values of 0.12, 0.24 and 0.96% and 2.95 were estimated. The number of samples required to determine the true value of either [Ca++] or pH in an individual cow was 5 and 1, respectively. Further, it was observed that, in investigations of blood Ca++ and blood pH in cattle, neither the use of electrolyte-balanced syringes interchangeable with sodium-heparin vacutainer nor the use of different blood sampling sites was to be recommended. IRMA SL did not correlate significantly with the chosen reference analyser (Stat Profile 5 Analyser; Nova Biomedical, Waltham, MA) with regard to plasma [Ca++] analyses (correlation coefficient r = -0.24, P = 0.22). However, a significant correlation coefficient (r = 0.63, P < 0.01) was found between analyses of pH performed on IRMA SL and Stat Profile 5 Analyser. Analysis on IRMA SL was very easy to perform. It could be a very useful aid in veterinary clinical practice, when determination of plasma pH in cattle is needed. The analyser should not yet be applied uncritically with respect to [Ca++] analyses in cattle.  相似文献   

12.
Blood plasma concentrations of estrone and progesterone, calcium and inorganic phosphorus were measured in 22 cows (Swedish Red and White Breed) from 4 weeks prepartum up to 6 days post partum. Ten cows with parturient paresis had Ca levels below 6 mg/100 ml. Data from plasma analyses in individual cows were grouped in the following periods: 28–22, 21–15, 14–8, 7–6, 5–4, 3, 2, 1 day(s) before parturition and 1, 2, 3–6 days after parturition. Statistical comparisons of the levels of the hormones and the ratio progesterone/estrone did not reveal any significant differences between the paretic and normal cows at any time period. The results do not support the theories that high systemic levels of estrogens or an imbalance between estrogen and progesterone predispose towards parturient paresis.  相似文献   

13.
OBJECTIVE: To determine whether dietary supplementation with clinoptilolite affects the incidence of parturient paresis and serum concentrations of total calcium (tCa), inorganic phosphorus (PO(4) (2)), magnesium (Mg2+), potassium (K+), and sodium (Na+) in dairy cattle. ANIMALS: 52 dairy cows. Procedure-Cows were placed into 3 groups. The first 2 groups (group A [n = 17] and group B [17]) were offered a concentrate supplemented with 1.25% and 2.5% clinoptilolite, respectively. The third (group C [n = 18]) served as a control and was offered the concentrate alone. The experiment started 1 month before parturition and lasted until the beginning of the next nonlactating period. Around the time of calving, all cows were monitored for the development of parturient paresis. Blood samples were taken at the commencement of the experiment, on the day of calving, and thereafter at monthly intervals to measure serum tCa, PO(4) (2), Mg2+, K+, and Na+ concentrations. Results-The incidence of parturient paresis in group B cows was significantly lower, compared with group C cows. However, serum concentrations of tCa, P(O4) (2), Mg2+, K+, and Na+ were not significantly affected by long-term supplementation with clinoptilolite. CONCLUSIONS AND CLINICAL RELEVANCE: In the context of this experiment, clinoptilolite supplementation at 2.5% appeared to have reduced the incidence of parturient paresis in dairy cows, suggesting that its effectiveness depends on the amount incorporated in the ration of cows. Addition of clinoptilolite in the concentrate of dairy cows during the nonlactating period could be used as a cost-effective preventive treatment for parturient paresis.  相似文献   

14.
This study investigated the process of PCV2-induced apoptosis and the effect of PCV2 inoculation on calcium homeostasis in piglet lymphocytes in vitro. PCV2-inoculated lymphocytes exhibited chromatin condensation, chromatin segregation, the appearance of membrane-enclosed apoptotic bodies, and DNA fragmentation. Moreover, the proportion of apoptotic cells increased significantly in PCV2-inoculated lymphocytes compared with controls. These results demonstrate that PCV2 induces lymphocyte apoptosis. Some evidence suggests that an alteration in the intracellular free Ca(2+) concentration ([Ca(2+)]i) could cause apoptosis. We measured elevated [Ca(2+)]i in PCV2-inoculated lymphocytes for 12 or 24h compared with controls. Our results support that PCV2-induced apoptosis may be relative to [Ca(2+)]i. In addition, calmodulin (CaM) was increased in PCV2-inoculated lymphocytes for 12h compared with controls. The amount of CaM-dependent protein kinase II (CaMKII) did not change with PCV2 inoculation. We infer that the increased [Ca(2+)]i can bind CaM protein, but functions independently of CaMKII. Inositol 1,4,5-trisphosphate receptor (IP3R)-1 mRNA expression increased with PCV2 inoculation, whereas plasma Ca(2+)-ATP4 mRNA expression decreased. A decreased Ca(2+)-ATP4 level may inhibit Ca(2+) efflux, and the increased IP3R-1 may trigger Ca(2+) release from the endoplasmic reticulum. Both of these changes may contribute to increased [Ca(2+)]i.  相似文献   

15.
In this study, we investigated the fluctuations of concentration of intracytoplasmic free Ca(2+) during in vitro maturation of caprine primary oocytes and its role in meiotic resumption. Oocytes that were extracted from caprine ovaries were cultured and allowed to mature in vitro to determine their developmental stages including germinal vesicle (GV), germinal vesicle breakdown (GVBD), metaphase of the first meiotic division (MI) and metaphase of the second meiotic division (MII). Intracytoplasmic free Ca(2+) turnovers of caprine oocytes at these different developmental stages were measured using the calcium fluorescent probe Fura-2/AM (C(44)H(47)N(3)O(24)) to investigate the dynamics of cytosolic free Ca(2+) during in vitro maturation of oocytes and the role of Ca(2+) in inducing the initiation of meiotic resumption of oocytes. Moreover, the oocytes were cultured in Ca(2+) culture medium and Ca(2+)-free culture medium to examine the effect of extracellular Ca(2+) on the oocyte maturation. The results indicated that Ca(2+) concentrations at GV, GVBD, MI and MII stages were 78.06, 147.41, 126.97 and 97.73 nmol/l, respectively, and that 86.30% of oocytes remained at the GV stage and no oocyte developed to MII in Ca(2+)-free culture medium, and 1.1% of oocytes stayed at the GV stage and 83.5% of oocytes developed to MII in Ca(2+) culture medium. These results suggest that the occurrence of GVBD and cell cycle progression to MI and MII stages are closely related to Ca(2+), and that extracellular Ca(2+) performs a specific function for the initiation of meiotic resumption in caprine oocytes.  相似文献   

16.
We have studied in the porcine endometrium the expression of oxytocin receptor (OTR) mRNA and the effect of progesterone (P4) on oxytocin/oxytocin receptor (OT/OTR) function concerning intracellular Ca2+ mobilisation ([Ca2+]i), prostaglandin F2alpha (PGF2alpha) and E2 (PGE2; PG) secretion. Tissue was taken from cyclic and early pregnant pigs (days 14-16). A higher expression of OTR mRNA (P < 0.05) was observed in the endometrium of cyclic than pregnant pigs. The stimulatory (P < 0.05) effect of OT (10(-7) M) on [Ca2+]i mobilisation was noticed within 15-60 s and 30-60 s in endometrial stromal cells of cyclic and pregnant pigs, respectively. In the presence of P4 (10(-5) M) basal and OT-stimulated [Ca2+]i concentrations decreased in stromal cells during luteolysis and pregnancy. In stromal cells P4 delayed mobilisation of [Ca2+]i in response to OT by 15 s during luteolysis and had no effect during pregnancy. In cyclic and pregnant epithelial cells OT stimulated mobilisation of [Ca2+]i in 45 s and 60 s, respectively. Oxytocin increased (P < 0.05) PGF2alpha secretion during luteolysis and pregnancy and PGE2 during luteolysis from endometrial slices. Progesterone did not inhibit this stimulatory effect. During luteolysis OT increased (P < 0.05) PGF2alpha in epithelial and stromal cells and PGE2 secretion in epithelial cells. In the presence of P4 this effect of OT was reduced only in stromal cyclic cells (6 h culture). The presence of P4 decreased the effect of OT on [Ca2+]i mobilisation only in stromal cells. We found that, in most conditions, P4 did not inhibit the OT-stimulated secretion of PG in the porcine endometrium.  相似文献   

17.
Summary Objective: Hypocalcaemia is a common finding in horses with enterocolitis and severe gastrointestinal disorders. The aims of this study were to investigate in colic horses (!))the parameters related to hypocalcaemia, (2))the influence of hypocalcaemia on outcome and (3))the possible beneficial effect of Ca(2+ )substitution. Design: Randomized controlled trial. Setting: Intensive care unit. Patients: One hundred forty-four horses that were admitted with an acute abdomen during a 1.5 year period were enrolled and daily evaluated for clinical criteria and whole blood ionized Ca levels. Colic horses with hypocalcaemia were randomly assigned to receive Ca(2+). Interventions: Analysis of heparinised whole blood samples. Horses that were assigned to be treated received 400 mEq Ca(2+) diluted in 10L of Ringer's lactate solution every 24 h until low reference range limits were obtained or until death. Measurements and main results: 88% of all colic patients showed blood ionized Ca levels below the reference range at the time of admission. Multivariable analysis revealed that the presence of reflux signs of endotoxaemia increased Packed Cell Volume (PCV) alkalinization of pH and the interaction PCV/pH all predispose colic horses to low ionized Ca(2+) levels at the time of admission. The Odds for developing ileus during hospitalization are ± 11.94 times larger for horses in the "very low" calcaemia interval in comparison with normocalcaemic horses. The Odds for fatal outcome are respectively ± 9.82 and 8.33 times larger for horses in the "very low" and "low" calcaemia interval. Ca(2+) substitution increased the probability of survival provided that Ca(2+) levels could be normalized. The lack of an upward calcaemia response despite repetitive Ca(2+) substitutions can be guarded as a poor ominous sign. Conclusions: Hypocalcaemia in colic horses is of prognostic relevance both with regard to survival as to the probability of development of ileus during hospitalization. This study shows the importance of routine measurement of ionized calcium levels in colic horses. Moreover correction of hypocalcaemia seems to improve clinical outcome.  相似文献   

18.
Fasciola hepatica causes biliary epithelial hyperplasia and obstructive jaundice in humans and animals. Using a planar lipid bilayer technique, we further characterized the single channel property of large conductance K(+)-permeable channels that were previously identified from F. hepatica. The single channel conductance was 254.7±17.9 pS under a symmetrical 200/200 mM (cis/trans) KCl gradient. Open state probability (P(o)) varied from channel to channel at a given membrane potential and Ca(2+) concentration, but increased with voltage (-60 to +40 mV) and cis Ca(2+) (1-200 μM). Under a near bi-ionic condition of 200 mM [K(+)](cis)/200 mM [Na(+)](trans), the permeability ratio of K(+) to Na(+) was 5.0. Charybdotoxin (1 μM) inhibited P(o), whereas tetraethylammonium reduced the conductance (K(D)=67.8mM). Taken together, the results show that the single channel properties of the large conductance K(+)-permeable channels in F. hepatica are similar to those of large conductance Ca(2+)-activated K(+) (BK) channels in general, but distinct from typical BK channels in the extent of voltage- and Ca(2+)-dependence, as well as permeability to Na(+). This study further reveals a variant BK channel in F. hepatica that could serve as a new drug target to treat fascioliasis.  相似文献   

19.
Photodynamic agents, due to their selective uptake by tumor cells and photon-dependent selective activation, have immense implications for cancer treatment. The present study provided direct evidence that the photon activation of chloro-aluminum phthalocyanine sulphonate (A1PcS4) in the presence of extracellular Ca2+ caused a rapid increase followed by a sustained increase in intracellular concentration of calcium ion ([Ca2+]i) in a small cell lung carcinoma (SCLC) cell line, SBC-3. The [Ca2+]i increase by photodynamic stimulation was completely inhibited by the removal of extracellular Ca2+ and reintroduction of extracellular Ca2+ immediately led to a rapid elevation of [Ca2+]i. However, the increase was not inhibited by application of Ni2+, nifedipine, or SK&F 96365, a receptor-mediated and voltage-dependent Ca2+ entry blocker. The photosensitizer A1PcS4 alone or light alone (4 min) had no effect on [Ca2+]i. Cytotoxicity examination by trypan blue exclusion test, however, suggested photodynamic stimulation-induced cell injury which was observed in both the presence and the absence of extracellular Ca2+. These results indicate that [Ca2+]i increase may not be mandatory for photodynamic stimulation-induced cell injury. Whether [Ca2+]i increase can accelerate, at least in part, cell death under the physiological condition, whether the mechanism(s) of cell death can be different in the presence and the absence of extracellular Ca2+, and whether [Ca2+]i increase can be totally unrelated to cell death await further work.  相似文献   

20.
Endothelin (ET), derived from the endothelium of blood vessels, is a potent vasoactive peptide. Although it has been reported to be involved in cardiovascular diseases, such as hypertension, the mechanism by which ET evokes vasoconstriction is still unclear. On the other hand, p42/p44 mitogen-activated protein kinase (MAPK) and p38 MAPK are activated by a variety of growth factors and cellular stresses, respectively. However, the role of p42/p44 MAPK and p38 MAPK on the ET-1-induced vasoconstriction is not fully understood. This study was undertaken to determine whether p42/p44 MAPK and p38 MAPK participate in the regulation of vascular smooth muscle contraction by ET-1. The isometric vasoconstriction and intracellular Ca(2+) ([Ca(2+)](i)) were simultaneously measured using CAF-100. Phosphorylation of myosin light chain (MLC) and p42/p44 MAPK, p38 MAPK were determined by Western blots. In rat thoracic aorta, ET-1 induced a sustained contraction. In contrast, [Ca(2+)](i) was decreased with time. Both PD98059, an inhibitor of p42/p44 MAPK, and SB203580, an inhibitor of p38 MAPK, partially attenuated ET-1-induced contractions in concentration-dependent manners. ET-1 increased phosphorylation of both p42/p44 MAPK and p38 MAPK, and PD98059 and SB203580 completely decreased phosphorylation of p42/p44 MAPK and p38 MAPK in response to ET-1 stimulation, respectively. On the other hand, PD98059 and SB203580 did not affect MLC phosphorylation in response to ET-1 stimulation. These results indicate that p38 MAPK, as well as p42/p44 MAPK, may partially regulate the ET-1-induced contraction through a MLC phosphorylation-independent pathway.  相似文献   

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