|
|
||||||||
AJP - Heart and Circulatory Physiology, Vol 258, Issue 6 1745-H1752, Copyright © 1990 by American Physiological Society
ARTICLES |
A. M. Vites and A. Pappano
Department of Pharmacology, University of Connecticut Health Center, Farmington 06032.
Inositol 1,4,5-trisphosphate (IP3) and caffeine evoked transient, reversible, and concentration-dependent increases in tension in saponin-treated chick atrial muscle. Contractures evoked by IP3 and caffeine were detected in solutions with 70 microM EGTA at pCa 7.0. In the presence of 7 mM EGTA, neither IP3 nor caffeine was able to evoke a contracture. Maximally effective concentrations of IP3 (20 microM) and caffeine (20 mM) developed tensions to approximately 44 and 83% of that elicited by pCa 5.0 (maximum tension = 100%), respectively. The IP3- or caffeine-induced contractures were consistently reproduced when the sarcoplasmic reticulum (SR) had previously been loaded with calcium. Preexposure to caffeine suppressed the following IP3-induced response. When ryanodine (1-10 microM) was present throughout the SR-loading cycle, the responses to IP3 and caffeine were prevented. However, when ryanodine was added after the SR was loaded with calcium, neither the response to IP3 nor that to caffeine was affected. These results are consistent with the hypothesis that ryanodine inhibition requires prior activation of the SR calcium-release channel. It is concluded that both IP3 and caffeine increased tension in the SR by releasing calcium from it. The effect of IP3 is consistent with its messenger role as a calcium-mobilizing agent.
This article has been cited by other articles:
![]() |
K. D. Garcia, T. Shah, and J. Garcia Immunolocalization of type 2 inositol 1,4,5-trisphosphate receptors in cardiac myocytes from newborn mice Am J Physiol Cell Physiol, October 1, 2004; 287(4): C1048 - C1057. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. Munakata, C. Stamm, I. Friehs, D. Zurakowski, D. B. Cowan, H. Cao-Danh, F. X. McGowan Jr, and P. J. del Nido Protective effects of protein kinase C during myocardial ischemia require activation of phosphatidyl-inositol specific phospholipase C Ann. Thorac. Surg., April 1, 2002; 73(4): 1236 - 1245. [Abstract] [Full Text] [PDF] |
||||
![]() |
G. Vassort Adenosine 5'-Triphosphate: a P2-Purinergic Agonist in the Myocardium Physiol Rev, April 1, 2001; 81(2): 767 - 806. [Abstract] [Full Text] [PDF] |
||||
![]() |
E. Carmeliet Cardiac Ionic Currents and Acute Ischemia: From Channels to Arrhythmias Physiol Rev, July 1, 1999; 79(3): 917 - 1017. [Abstract] [Full Text] [PDF] |
||||
![]() |
T. Saeki, J.-B. Shen, and A. J. Pappano Inositol-1,4,5-trisphosphate increases contractions but not L-type calcium current in guinea pig ventricular myocytes Cardiovasc Res, March 1, 1999; 41(3): 620 - 628. [Abstract] [Full Text] [PDF] |
||||
![]() |
B. Felzen, M. Shilkrut, H. Less, I. Sarapov, G. Maor, R. Coleman, R. B. Robinson, G. Berke, and O. Binah Fas (CD95/Apo-1)–Mediated Damage to Ventricular Myocytes Induced by Cytotoxic T Lymphocytes From Perforin-Deficient Mice : A Major Role for Inositol 1,4,5-Trisphosphate Circ. Res., March 9, 1998; 82(4): 438 - 450. [Abstract] [Full Text] [PDF] |
||||
![]() |
L. Protas, J.-B. Shen, and A. J. Pappano Carbachol Increases Contractions and Intracellular Ca++ Transients in Guinea Pig Ventricular Myocytes J. Pharmacol. Exp. Ther., January 1, 1998; 284(1): 66 - 74. [Abstract] [Full Text] |
||||
![]() |
E. Podrasky, D. Xu, and B. T. Liang A novel phospholipase C- and cAMP-independent positive inotropic mechanism via a P2 purinoceptor Am J Physiol Heart Circ Physiol, November 1, 1997; 273(5): H2380 - H2387. [Abstract] [Full Text] [PDF] |
||||
![]() |
T. Saeki, J.-B. Shen, and A. J. Pappano Carbachol promotes Na+ entry and augments Na/Ca exchange current in guinea pig ventricular myocytes Am J Physiol Heart Circ Physiol, October 1, 1997; 273(4): H1984 - H1993. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. Zhang, D. Turnbaugh, D. Cofie, S. Dogan, H. Koshida, R. Fugate, and D. C. Kem Protein Kinase C Modulation of Cardiomyocyte Angiotensin II and Vasopressin Receptor Desensitization Hypertension, February 1, 1996; 27(2): 269 - 275. [Abstract] [Full Text] |
||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Visit Other APS Journals Online |