DIFFERENTIAL EFFECTS OF ADENOSINE AND NITROGLYCERIN ON THE ACTION POTENTIALS OF LARGE AND SMALL CORONARY-ARTERIES

被引:178
作者
HARDER, DR [1 ]
BELARDINELLI, L [1 ]
SPERELAKIS, N [1 ]
RUBIO, R [1 ]
BERNE, RM [1 ]
机构
[1] UNIV VIRGINIA, SCH MED, DEPT PHYSIOL, CHARLOTTESVILLE, VA 22901 USA
关键词
D O I
10.1161/01.RES.44.2.176
中图分类号
R5 [内科学];
学科分类号
1002 ; 100201 ;
摘要
The authors used intracellular microelectrodes to study some membrane electrical properties of isolated large (>1.0 mm) and small (<500 μm) coronary arteries of the dog. The resting membrane potential (E(m)) was not significantly different in large arteries and small arteries (average of -56 mV and -53 mV, respectively) nor was the input resistance (9 MΩ and 10MΩ, respectively). Spontaneous action potentials were not present in vessels of either size, and action potentials could not be induced by electrical stimulation. Addition of tetraethylammonium ion (TEA, 10mm) rapidly induced overshooting action potentials on electrical stimulation in both large and small arteries. The amplitude of the action potential increased as a function of log [Ca2+]0, the slope of the curve being 30 mV/decade in the large and small arteries, thus demonstrating that Ca2+ carries most of the inward current during the action potential. Verapamil (10-6M) blocked these Ca2+-dependent action potentials in both the large and small coronaries. Adenosine (10-5M)blocked the action potential in the small coronary arteries but had no effect on the action potential in the large coronary arteries. In contrast, nitroglycerin(10-5M)blocked the action potential in the large coronary arteries but not in the small arteries. The results of this study demonstrate that adenosine blocks Ca2+ inward current preferentially in small coronary arteries, and nitroglycerin blocks the Ca2+ current preferentially in large coronary arteries. These observations are consonant with a role for adenosine in the metabolic regulation of coronary blood flow in the small coronary vessels.
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页码:176 / 182
页数:7
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