[Vasonatrin peptide attenuates the enhancement of electrically-induced intracellular calcium transient by isoproterenol in rat cardiac myocytes].
The purpose of this study was to investigate the effects of vasonatrin peptide (VNP) on electrically-induced intracellular calcium ([Ca(2+)](i)) transient and mechanism of the effects in the cardiac myocytes. The [Ca(2+)](i) transient was measured with a fluoremetric method. The effects of HS-142-1, 8-Br-cGMP and methylene blue (MB) on [Ca(2+)](i) transient in cardiac myocytes were also determined. Isoproterenol (Iso) at 10(-10)~10(-6) mol/L augmented electrically-induced [Ca(2+)](i) transient dose-dependently, which was (13+/-8)% (P>0.05), (26+/-13)% (P< 0.05), (66+/-10)% (P<0.01), (150+/-10)% (P<0.01) and (300+/-25)% (P<0.01), respectively. These effects were blocked by an beta-adrenergic bloker propranolol (10(-6) mol/L). The effect of Iso (10(-8) mol/L) on [Ca(2+)](i) transient was attenuated in a dose-dependent manner by VNP at 10(-10)~10(-6) mol/L, which was (99+/-3)% (P>0.05), (96+/-2)% (P<0.05), (84+/-6)% (P<0.01), (66+/-3)% (P<0.01) and (62+/-3)% (P<0.01), respectively. 8-Br-cGMP (10(-7)~10(-3) mol/L) aslo attenuated 10(-8) mol/L Iso-induced [Ca(2+)](i) transient dose-dependent. The effect of VNP on [Ca(2+)](i) transient was almost abolished in the presence of HS-142-1 (2x10(-5) mol/L), an antagonist of the natriuretic peptide guanylate cyclase (GC) receptors. MB (10(-5) mol/L), an inhibitor of GC, not only blocked the effect of VNP in myocytes, but also augmented electrically-induced [Ca(2+)](i) transient. VNP and HS-142-1 themselves did not change the [Ca(2+)](i) transient in the cardiac myocytes significantly. But MB augmented the [Ca(2+)](i) transient in the cardiac myocytes significantly. These results suggest that VNP attenuates [Ca(2+)](i) transient induced by Iso. This effect is possibly achieved by binding VNP with the natriuretic peptide GC receptors in the myocytes, leading to an increase in intracellular cGMP.
Guo
Hai-Tao
HT
Department of Physioloy, Fourth Military Medical University, Xi'an 710032 China.
Zhu
Miao-Zhang
MZ
Zhang
Rong-Huai
RH
Bi
Hui
H
Zhang
Bo
B
Zhang
Hai-Feng
HF
Yu
Jun
J
Lu
Shun-Yan
SY
Pei
Jian-Ming
JM
D000818:Animals; D009320:Atrial Natriuretic Factor / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism; D006152:Cyclic GMP / Q000378:metabolism; D003864:Depression, Chemical; D005260:Female; D006162:Guanylate Cyclase / Q000378:metabolism*; D007545:Isoproterenol / Q000494:pharmacology*; D008297:Male; D032383:Myocytes, Cardiac / Q000378:metabolism; D051381:Rats; D017461:Receptors, Atrial Natriuretic Factor / Q000378:metabolism*
D015220:Calcium Channels; C068986:ventricular natriuretic peptide, eel; D009320:Atrial Natriuretic Factor; D006162:Guanylate Cyclase; D017461:Receptors, Atrial Natriuretic Factor; C091715:atrial natriuretic factor receptor A; D006152:Cyclic GMP; D007545:Isoproterenol; D002118:Calcium