Effects of norepinephrine and isopentenyladenosine on Na~+/Ca~(2+) exchangecurrents in isol

• 作 者: 顿文 吴博威 赵荣瑞
• 机 构: 山西医科大学生理教研室
• 出 处: Acta Pharmacologica Sinica
• 发表日期: 1998年02期
• 关键词: 异丙肾上腺素 膜片箝 去甲肾上腺素 妥拉 全细胞电压钳 guinea 普萘洛尔 交换电流 norepinephrine 膜电位

目的：研究去甲肾上腺素（ＮＥ）和异丙肾上腺素（Ｉｓｏ）对Ｎａ＋／Ｃａ２＋交换电流的影响及受体调控机制．方法：应用全细胞电压钳技术的斜坡脉冲程序，测定离体豚鼠心肌细胞准稳态电流电压关系曲线．结果：ＮＥ０００５，００５和５μｍｏｌ·Ｌ－１分别使膜电位＋５０ｍＶ时的Ｎｉ２＋敏感电流增加２９％±９％，７２％±１１％和１２０％±３１％；Ｉｓｏ１５，１５０和１５００ｎｍｏｌ·Ｌ－１分别使该电流增加２８％±２８％，５６％±１３％和１０２％±１２％．ＮＥ和Ｉｓｏ的这种增强效应能被普萘洛尔１０μｍｏｌ·Ｌ－１完全阻断，而酚妥拉明５０μｍｏｌ·Ｌ－１无此作用．结论：ＮＥ和Ｉｓｏ通过兴奋心脏β肾上腺素受体使Ｎａ＋／Ｃａ２＋交换电流增加．

Objective: To study the effects of norepinephrine (NE) and isoproterenol (Iso) on Na + / Ca2 + exchange current and the mechanism of its receptor regulation. Methods: The whole-cell voltage-clamp technique was used to measure the quasi-steady-state current-voltage curve of isolated guinea pig cardiomyocytes. Results: NE0005,005 and 5μmol·L-1 increased the Ni2 + sensitive current by 29% ± 9%, 72% ± 11% and 120% ± 31% at membrane potential + 50mV, respectively. Iso15,150 and 1500 nmol·L-1 increased the current by 28% ± 28%, 56% ± 13% and 102% ± 12%, respectively. This enhancement of NE and Iso was completely blocked by propranolol at 10 μmol·L -1, whereas phentolamine 50 μmol·L -1 did not. CONCLUSIONS: NE and Iso increase Na + / Ca2 + exchange currents by excitatory beta-adrenergic receptors in the heart.