Regulation of L-type Calcium Channel Current by Somatostatin in Guinea-Pig Gastric Myocytes

• 영문명: Regulation of L-type Calcium Channel Current by Somatostatin in Guinea-Pig Gastric Myocytes
• 발행기관: 대한생리학회-대한약리학회
• 저자명: Young Chul Kim Jae Hoon Sim Sang Jin Lee Tong Mook Kang Sung Joon Kim Seung Ryul Kim Sei Jin Youn Sa
• 간행물 정보: 『The Korean Journal of Physiology & Pharmacology』제9권 제2호, 103~108쪽, 전체 6쪽
• 주제분류: 의약학 > 의학일반
• 파일형태: PDF
• 발행일자: 2005.01.01

영문 초록

To study the direct effect of somatostatin (SS) on calcium channel current (I_Ba) in guinea-pig gastric myocytes, I_Ba was recorded by using whole-cell patch clamp technique in single smooth muscle cells. Nicardipine (1μM), a L-type Ca²⁺ channel blocker, inhibited I_Ba by 98⁑1.9% (n=5), however I_Ba was decreased in a reversible manner by application of SS. The peak I_Ba at 0 mV were decreased to 95⁑1.1, 92⁑1.9, 82⁑4.0, 66⁑5.8, 10⁑2.9% at 10^⁣10, 10^⁣9, 10^⁣8, 10^⁣7, 10^⁣5 M of SS, respectively (n=3∼6; mean⁑SEM). The steady-state activation and inactivation curves of I_Ba as a function of membrane potentials were well fitted by a Boltzmann equation. Voltage of half-activation (V_0.5) was ⁣12⁑0.5 mV in control and ⁣11⁑1.9 mV in SS treated groups (respectively, n=5). The same values of half-inactivation were ⁣35⁑1.4 mV and ⁣35⁑1.9 mV (respectively, n=5). There was no significant difference in activation and inactivation kinetics of I_Ba by SS. Inhibitory effect of SS on I_Ba was significantly reduced by either dialysis of intracellular solution with GDP_βS, a non-hydrolysable G protein inhibitor, or pretreatment with pertussis toxin (PTX). SS also decreased contraction of guinea-pig gastric antral smooth muscle. In conclusion, SS decreases voltage-dependent L-type calcium channel current (VDCC_L) via PTX- sensitive signaling pathways in guinea-pig antral circular myocytes.