Evidence for adenosine receptor-mediated hyperpolarization in coronary smooth muscle.
The effects of adenosine and its analogues, 5'-N-ethyl-carboxamidoadenosine (NECA) and 2-chloroadenosine (CAD), were studied on resting membrane potential of bovine coronary artery. The resting membrane potential averaged -51 +/- 1 mV. KCl (50 mM) caused a significant decrease of the resting membrane potential (-30 +/- 1 mV). In separate series of experiments suffusion of the arterial strips with adenosine, NECA, or CAD, at concentrations of 10(-5)M, produced significant increases in resting membrane potential (-68 +/- 1, -80 +/- 2, and -88 +/- 4 mV, respectively). The hyperpolarizing responses to adenosine, NECA, and CAD appeared to have been mediated by an adenosine receptor, since they were blocked by the adenosine receptor antagonist, 8-phenyltheophylline (10(-5) M). The data suggest that activation of an adenosine receptor can result in hyperpolarization of coronary smooth muscle cells.
Sabouni
M H
MH
Department of Pharmacology, School of Medicine, East Carolina University, Greenville, North Carolina 27858-4354.
Hargittai
P T
PT
Lieberman
E M
EM
Mustafa
S J
SJ
D015762:2-Chloroadenosine / Q000494:pharmacology; D000241:Adenosine / Q000494:pharmacology; D019830:Adenosine-5'-(N-ethylcarboxamide); D000818:Animals; D002417:Cattle; D003331:Coronary Vessels / Q000502:physiology*; D004594:Electrophysiology; D008564:Membrane Potentials / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000502:physiology; D011189:Potassium Chloride / Q000494:pharmacology; D011983:Receptors, Purinergic / Q000502:physiology*; D013806:Theophylline / Q000031:analogs & derivatives / Q000494:pharmacology; D014665:Vasodilator Agents / Q000494:pharmacology
D011983:Receptors, Purinergic; D014665:Vasodilator Agents; D015762:2-Chloroadenosine; D019830:Adenosine-5'-(N-ethylcarboxamide); D011189:Potassium Chloride; D013806:Theophylline; C028322:8-phenyltheophylline; D000241:Adenosine