geoscience.net logo
+ Resolve Article
+ Follow Us
Follow on FacebookFollow on Facebook
Follow on TwitterFollow on Twitter

+ Translate
+ Subscribe to Site Feed
GeoScience Most Shared ContentMost Shared Content

The effects of calcium antagonists on calcium overload contractures in embryonic chick myocytes induced by ouabain and veratrine


, : The effects of calcium antagonists on calcium overload contractures in embryonic chick myocytes induced by ouabain and veratrine. British Journal of Pharmacology 97(1): 83-94

The protective effects of some calcium antagonists against different forms of calcium overload contracture were investigated in embryonic chick cardiac myocytes. Tetrodotoxin-sensitive sodium currents were recorded from the myocytes by the whole-cell voltage-clamp technique. Although the peak current was attenuated by veratrine, the inactivation process was markedly inhibited, resulting in a large increase in the the total inward current. Action potentials were prolonged by veratrine, automaticity was inhibited and the membrane potential depolarized from -79 to around -45 mV. Measurements of contraction were made from aggregates of myocytes using a video edge detection technique which quantified edge movement. Veratrine caused an initial positive inotropism then inhibited automaticity of aggregates with subsequent development of a tonic contracture to around 300% of the twitch contraction. Veratrine-induced contractures were not significantly affected by 10 .mu.M diltiazem or verapamil. Nifedipine (5 .mu.M), nimodipine (5 .mu.M) and ryanodine (5 .mu.M) also had little effect whilst nicardipine and flunarizine caused a concentration-dependent inhibition of veratrine-induced contractures with IC50 s of 3 .mu.M and 2 .mu.M respectively. Veratrine-induced contractures were found to be very sensitive to extracellular calcium concentration with an EC50 of 32 .mu.M. Edge movement associated with beating of the myocytes was much less sensitive to calcium (EC50 = 1 mM). Submaximal veratrine contractures in 20-50 .mu.M extracellular calcium were not potentiated by 1 .mu.M Bay K 8644. Tetrodotoxin also inhibited veratrine-induced contractures but did not affect contractions induced by ouabain in the presence of 10 diltiazem. Ouabain-induced contractures were also inhibited by nicardipine and flunarizine indicating that these drugs can protect against calcium overload in embryonic chick heart by a mechanism independent of the normal form of voltage-sensitive sodium or calcium channels.

US$19.90

PMID: 2470461

DOI: 10.1111/j.1476-5381.1989.tb11927.x


Other references

Pitchumoni, C.S., 1984: Special problems of tropical pancreatitis. Clinics in Gastroenterology 13(3): 941-959

Dhanireddy, R.; Senger, D.; Mukherjee, B.B.; Mukherjee, A.B., 1993: Osteopontin in human milk from mothers of premature infants. Acta Paediatrica 82(10): 821-822

Lillard, A.S.; Peterson, J., 2011: The immediate impact of different types of television on young children's executive function. The goal of this research was to study whether a fast-paced television show immediately influences preschool-aged children's executive function (eg, self-regulation, working memory). Sixty 4-year-olds were randomly assigned to watch a fast-pa...

Ford, J.H.; Turner, A.; Yoshii, A., 2002: Information requirements of genomics researchers from the patient clinical record. The integration of bioinformatics and clinical informatics requires the assimilation of genomic information into the clinical record, as well as an understanding of the information needs of genomics researchers. This paper focuses on a methodology...

Dennert, G., 1974: Effector mechanisms of cell-mediated immunity to xenogeneic cell antigens. Journal of Immunology 113(1): 201-208

Davis, B.; Razo, A.; Nothnagel, E.; Chen, M.; Talbot, P., 2015: Unexpected nicotine in Do-it-Yourself electronic cigarette flavourings. Tobacco Control 25(E1): E67-E68

Ngo, T.; Doughty, C., 2011: Progressive unilateral arm weakness in a 7-year-old boy. A child with joint or extremity pain is a common presentation to the emergency department. Often, there is some element to the patient's history, whether it is trauma or some other significant history, which leads to a likely diagnosis. When...

Jaber, L.; Dolfin, T.; Shohat, T.; Halpern, G.J.; Reish, O.; Fejgin, M., 2000: Prenatal diagnosis for detecting congenital malformations: acceptance among Israeli Arab women. A high rate of consanguineous marriages exists within the Israeli Arab community, with approximately half occurring between first cousins. This contributes towards a high incidence of congenital malformations and autosomal recessive diseases, many...

Malhi, R.; Patni, P.; Bapna, D.; Arora, R.; Singh, V., 1981: Effect of storage on wool quality. I. Tensile and bulk resiliency behavior of stored wool fibres. Indian journal of textile research 6(3): 129-132

Kremer, BP., 1982: Algen/wirbellosen-endosymbiosen aspekte zur biologie interspezifischer assoziationen. Symbioses between unicellular algae and aquatic invertebrates are a widespread biological phenomenon including animal partners ranging from Protozoa up to the Urochordata and algae from at least 8 different classes. The establishment of an endosym...