Ca2+-induced Ca2+ Release from Sarcoplasmic Reticulum Negatively Regulates Myocytic ANP Release in Beating Rabbit Atria.
- Author:
Dan LI
1
;
He Xiu QUAN
;
Jin Fu WEN
;
Jing Yu JIN
;
Sung Hun PARK
;
Sun Young KIM
;
Sung Zoo KIM
;
Kyung Woo CHO
Author Information
1. Department of Physiology, Institute for Medical Sciences, Institute for Basic Sciences, Jeonbug National University Medical School, Jeonju 561-180, Korea. kwcho@chonbuk.ac.kr
- Publication Type:Original Article
- Keywords:
Atrial natriuretic peptide;
L-type Ca2+ channels;
Sarcoplasmic reticulum Ca2+ release
- MeSH:
Atrial Natriuretic Factor*;
Blood Pressure;
Nifedipine;
Ryanodine;
Sarcoplasmic Reticulum*;
Stroke Volume;
Thapsigargin
- From:The Korean Journal of Physiology and Pharmacology
2005;9(2):87-94
- CountryRepublic of Korea
- Language:English
-
Abstract:
It is not clear whether Ca2+-induced Ca2+ release from the sarcoplasmic reticulum (SR) is involved in the regulation of atrial natriuretic peptide (ANP) release. Previously, we have shown that nifedipine increased ANP release, indicating that Ca2+ entry via voltage-gated L-type Ca2+ channel activation decreases ANP release. The purpose of the present study was two-fold: to define the role of SR Ca2+ release in the regulation of ANP release and whether Ca2+ entry via L-type Ca2+ channel is prerequisite for the SR-related effect on ANP release. Experiments were performed in perfused beating rabbit atria. Ryanodine, an inhibitor of SR Ca2+ release, increased atrial myocytic ANP release (8.69+/-3.05, 19.55+/-1.09, 27.31+/-3.51, and 18.91+/-4.76% for 1, 2, 3, and 6microM ryanodine, respectively; all P< 1) with concomitant decrease in atrial stroke volume and pulse pressure in a dose-dependent manner. In the presence of thapsigargin, an inhibitor of SR Ca2+ pump, ryanodine-induced increase in ANP release was not observed. Thapsigargin attenuated ryanodine-induced decrease in atrial dynamic changes. Blockade of L-type Ca2+ channel with nifedipine abolished ryanodine-induced increase in ANP release (0.69+/-5.58% vs. 27.31+/-3.51%; P< 0.001). In the presence of thapsigargin and ryanodine, nifedipine increased ANP release and decreased atrial dynamics. These data suggest that Ca2+-induced Ca2+ release from the SR is inversely involved in the regulation of atrial myocytic ANP release.
