The role of Na(+)-Ca2+ exchange in activation of excitation-contraction coupling in rat ventricular myocytes - PubMed (original) (raw)
The role of Na(+)-Ca2+ exchange in activation of excitation-contraction coupling in rat ventricular myocytes
J A Wasserstrom et al. J Physiol. 1996.
Abstract
1. The purpose of this study was to determine whether mechanisms other than Ca2+ influx via L-type Ca2+ current (ICa) might contribute to activation of contraction in rat ventricular myocytes. The whole-cell voltage-clamp technique was used with normal transmembrane K+ and Na+ gradients at 34 degrees C. The sarcoplasmic reticulum (SR) was conditioned with one to three prepulses to +100 mV for 100 ms. 2. Cell shortening (delta L) increased with test voltage up to a plateau level at about +20 mV, beyond which cell shortening remained fairly constant, thus describing a sigmoidal voltage dependence. This relationship was obtained when holding potential (Vh) was either -40 or -70 mV; however, greater shortening was obtained at the more negative Vh. 3. The sigmoidal V-delta L relationship was converted to a bell shape following the magnitude of ICa when internal Cs+ was substituted for K+ and when the temperature was reduced to 22 degrees C. 4. At 34 degrees C, block of ICa with nifedipine (10 microM) decreased shortening by about 50% but did not alter the voltage dependence of delta L when Vh was either -40 or -70 mV. Addition of Ni2+ (4-5 mM) blocked all remaining contractions. 5. When cell shortening was triggered by an action potential voltage clamp, there was again about 50% of the contraction that was insensitive to nifedipine but was blocked by Ni2+. 6. Our results demonstrate that there is a significant contribution of a nifedipine-insensitive mechanism to the activation of contraction. This mechanism is likely to be reverse mode Na(+)-Ca2+ exchange since it appears to be sensitive to both voltage and Ni2+. We conclude that a contribution of reverse Na(+)-Ca2+ exchange to activation of excitation-contraction coupling occurs in rat heart at near-physiological conditions which include warm temperatures, normal transmembrane Na+ and K+ gradients and activation in response to an action potential.
Similar articles
- The effect of internal sodium and caesium on phasic contraction of patch-clamped rabbit ventricular myocytes.
Levi AJ, Mitcheson JS, Hancox JC. Levi AJ, et al. J Physiol. 1996 Apr 1;492 ( Pt 1)(Pt 1):1-19. doi: 10.1113/jphysiol.1996.sp021284. J Physiol. 1996. PMID: 8730578 Free PMC article. - Regulation of unloaded cell shortening by sarcolemmal sodium-calcium exchange in isolated rat ventricular myocytes.
Bouchard RA, Clark RB, Giles WR. Bouchard RA, et al. J Physiol. 1993 Sep;469:583-99. doi: 10.1113/jphysiol.1993.sp019831. J Physiol. 1993. PMID: 8271217 Free PMC article. - Activation of contraction in cat ventricular myocytes: effects of low Cd(2+) concentration and temperature.
Wasserstrom JA, Vites AM. Wasserstrom JA, et al. Am J Physiol. 1999 Aug;277(2):H488-98. doi: 10.1152/ajpheart.1999.277.2.H488. Am J Physiol. 1999. PMID: 10444473 - Evidence that reverse Na-Ca exchange can trigger SR calcium release.
Litwin S, Kohmoto O, Levi AJ, Spitzer KW, Bridge JH. Litwin S, et al. Ann N Y Acad Sci. 1996 Apr 15;779:451-63. doi: 10.1111/j.1749-6632.1996.tb44820.x. Ann N Y Acad Sci. 1996. PMID: 8659861 Review. - Action potential duration modulates calcium influx, Na(+)-Ca2+ exchange, and intracellular calcium release in rat ventricular myocytes.
Clark RB, Bouchard RA, Giles WR. Clark RB, et al. Ann N Y Acad Sci. 1996 Apr 15;779:417-29. doi: 10.1111/j.1749-6632.1996.tb44817.x. Ann N Y Acad Sci. 1996. PMID: 8659858 Review.
Cited by
- Modeling Na+-Ca2+ exchange in the heart: Allosteric activation, spatial localization, sparks and excitation-contraction coupling.
Chu L, Greenstein JL, Winslow RL. Chu L, et al. J Mol Cell Cardiol. 2016 Oct;99:174-187. doi: 10.1016/j.yjmcc.2016.06.068. Epub 2016 Jul 2. J Mol Cell Cardiol. 2016. PMID: 27377851 Free PMC article. - Junctional cleft [Ca²⁺]i measurements using novel cleft-targeted Ca²⁺ sensors.
Despa S, Shui B, Bossuyt J, Lang D, Kotlikoff MI, Bers DM. Despa S, et al. Circ Res. 2014 Jul 18;115(3):339-47. doi: 10.1161/CIRCRESAHA.115.303582. Epub 2014 May 28. Circ Res. 2014. PMID: 24871564 Free PMC article. - Na/Ca exchange and contraction of the heart.
Ottolia M, Torres N, Bridge JH, Philipson KD, Goldhaber JI. Ottolia M, et al. J Mol Cell Cardiol. 2013 Aug;61:28-33. doi: 10.1016/j.yjmcc.2013.06.001. Epub 2013 Jun 12. J Mol Cell Cardiol. 2013. PMID: 23770352 Free PMC article. Review. - Na⁺ transport in the normal and failing heart - remember the balance.
Despa S, Bers DM. Despa S, et al. J Mol Cell Cardiol. 2013 Aug;61:2-10. doi: 10.1016/j.yjmcc.2013.04.011. Epub 2013 Apr 19. J Mol Cell Cardiol. 2013. PMID: 23608603 Free PMC article. Review. - Cardiac sodium-calcium exchange and efficient excitation-contraction coupling: implications for heart disease.
Goldhaber JI, Philipson KD. Goldhaber JI, et al. Adv Exp Med Biol. 2013;961:355-64. doi: 10.1007/978-1-4614-4756-6_30. Adv Exp Med Biol. 2013. PMID: 23224894 Free PMC article. Review.
References
- J Membr Biol. 1978 Dec 15;44(2):159-86 - PubMed
- J Physiol. 1995 Apr 1;484 ( Pt 1):107-22 - PubMed
- Circ Res. 1987 Jul;61(1):148-54 - PubMed
- J Physiol. 1987 Mar;384:199-222 - PubMed
- Science. 1987 Dec 4;238(4832):1419-23 - PubMed
Publication types
MeSH terms
Substances
LinkOut - more resources
Full Text Sources
Research Materials
Miscellaneous