Increase of L-type Calcium Current by cGMP-dependent Protein Kinase Regulates in Rabbit Ventricular Myocytes

• 영문명: Increase of L-type Calcium Current by cGMP-dependent Protein Kinase Regulates in Rabbit Ventricular Myocytes
• 발행기관: 대한생리학회-대한약리학회
• 저자명: Jin Han Nari Kim Euiyong Kim Wonkyung Ho Yung E Earm Hankyoun Kim
• 간행물 정보: 『The Korean Journal of Physiology & Pharmacology』제2권 제6호, 733~742쪽, 전체 10쪽
• 주제분류: 의약학 > 의학일반
• 파일형태: PDF
• 발행일자: 1998.01.01

영문 초록

Background: We have previously reported that not only cGMP but also 8-Br-cGMP or 8-pCPT-cGMP, specific and potent stimulators of cGMP-dependent protein kinase (cGMP-PK), increased basal L-type calcium current (I_Ca) in rabbit ventricular myocytes. Our findings in rabbit ventricular myocytes were entirely different from the earlier findings in different species, suggesting that the activation of cGMP-PK is involved in the facilitation of I_Ca by cGMP. However, there is no direct evidence that cGMP-PK can stimulate I_Ca in rabbit ventricular myocytes. In this report, we focused on the direct effect of cGMP-PK on I_Ca in rabbit ventricular myocytes. Methods and Results: We isolated single ventricular myocytes of rabbit hearts by using enzymatic dissociation. Regulation of I_Ca by cGMP-PK was investigated in rabbit ventricular myocytes using whole-cell voltage clamp method. I_Ca was elicited by a depolarizing pulse to ⁢10 mV from a holding potential of ⁣40 mV. Extracellular 8-(4-Chlorophenylthio)-guanosine-3 ,5 -cyclic monophosphate (8-pCPT-cGMP), potent stimulator of cGMP-dependent protein kinase (cGMP-PK), increased basal I_Ca. cGMP-PK also increased basal I_Ca. The stimulation of basal I_Ca by cGMP-PK required both 8-Br-cGMP in low concentration and intracellular ATP to be present. The stimulation of basal I_Ca by cGMP-PK was blocked by heat inactivation of the cGMP-PK and by bath application of 8- (4-chlorophenylthio)-guanosine-3 ,5 -cyclic monophosphate, Rp-isomer (Rp-pCPT-cGMP), a phosphodiesterase-resistant cGMP-PK inhibitor. When I_Ca was increased by internal application of cGMP-PK, IBMX resulted in an additional stimulation of I_Ca. In the presence of cGMP-PK, already increased I_Ca was potentiated by bath application of isoprenaline or forskolin or intracellular application of cAMP. Conclusions: We present evidence that cGMP-PK stimulated basal I_Ca by a direct phosphorylation of L-type calcium channel or associated regulatory protein in rabbit ventricular myocytes.

키워드

cGMP-dependent protein kinase (cGMP-PK) L-type calcium current (I_Ca) Rabbit ventricular myocytes Whole-cell voltage clamp