Publication: Myofilament response to Ca<sup>2+</sup>and Na<sup>+</sup>/H<sup>+</sup>exchanger activity in sex hormone-related protection of cardiac myocytes from deactivation in hypercapnic acidosis
Issued Date
2007-02-01
Resource Type
ISSN
15221490
03636119
03636119
Other identifier(s)
2-s2.0-33846815376
Rights
Mahidol University
Rights Holder(s)
SCOPUS
Bibliographic Citation
American Journal of Physiology - Regulatory Integrative and Comparative Physiology. Vol.292, No.2 (2007)
Suggested Citation
Tepmanas Bupha-Intr, Jonggonnee Wattanapermpool, James R. Peña, Beata M. Wolska, R. J. Solaro Myofilament response to Ca<sup>2+</sup>and Na<sup>+</sup>/H<sup>+</sup>exchanger activity in sex hormone-related protection of cardiac myocytes from deactivation in hypercapnic acidosis. American Journal of Physiology - Regulatory Integrative and Comparative Physiology. Vol.292, No.2 (2007). doi:10.1152/ajpregu.00376.2006 Retrieved from: https://repository.li.mahidol.ac.th/handle/20.500.14594/24253
Research Projects
Organizational Units
Authors
Journal Issue
Thesis
Title
Myofilament response to Ca<sup>2+</sup>and Na<sup>+</sup>/H<sup>+</sup>exchanger activity in sex hormone-related protection of cardiac myocytes from deactivation in hypercapnic acidosis
Other Contributor(s)
Abstract
Compared to sham-operated controls, myofilaments from hearts of ovariectomized (OVX) rats demonstrate an increase in Ca2+sensitivity with no change in maximum tension (Wattanapermpool J and Reiser PJ. Am J Physiol 277: H467-H473, 1999). To test the significance of this modification in intact cells, we compared intracellular Ca2+transients and shortening of ventricular myocytes isolated from sham and 10-wk OVX rats. There was a decrease in the peak Ca2+transient with prolonged 50% decay time in OVX cardiac myocytes without changes in the resting intracellular Ca2+concentration. Percent cell shortening was also depressed, and relaxation was prolonged in cardiac myocytes from OVX rats compared with shams. Ovariectomy induced a sensitization of the myofilaments to Ca2+. Hypercapnic acidosis suppressed the shortening of OVX myocytes to a lesser extent than that detected in shams. Moreover, a larger compensatory increase in %cell shortening was obtained in OVX myocytes during prolonged acidosis. The elevated compensation in cell shortening was related to a higher amount of increase in the amplitude of the Ca2+transient in OVX myocytes. However, these differences in Ca2+transients and %cell shortening were no longer evident in the presence of 1 μM cariporide, a specific inhibitor of Na+/H+exchanger type 1 (NHE1). Our results indicate that deprivation of female sex hormones modulates the intracellular Ca2+concentration in cardiac myocytes, possibly via an increased NHE1activity, which may act in concert with Ca2+hypersensitivity of myofilament activation as a determinant of sex differences in cardiac function. Copyright © 2007 the American Physiological Society.