Effects of angiotensin II on membrane current in cardiac Purkinje fibers |
| |
Authors: | RS Kass ML Blair |
| |
Institution: | Department of Physiology, Box 642, Univesity of Rochester School of Medicine and Dentistry, 601 Elmwood Avenue, Rochester, New York 14642, USA |
| |
Abstract: | We studied the actions of the octapeptide hormone angiotensin II (AII) on isolated cardiac Purkinje fibers. AII (1 to 75 nm) increased the height and duration of the plateau phase of the action potential and increased the strength of contraction in these preparations. These effects were not blocked by propranolol (10?6m). A two-microelectrode voltage clamp technique combined with simultaneous tension measurements was used to study the AII-induced changes in membrane current and contractile activation. AII enhanced peak tension and promoted an inward shift in the net membrane current-voltage relation at test voltages between ?40 and 0 mV. The inward shift in current was maintained for the duration of the 500 ms test voltage step. The AII-induced current shift was reduced or abolished when external calcium concentration was decreased from 5.4 mm to 1.8 mm, and was inhibited by the calcium antagonist D600. |
| |
Keywords: | Purkinje fibres Voltage clamp Angiotensin II |
本文献已被 ScienceDirect 等数据库收录! |
|