[Effect of adenosine and ATP on electrogenesis and contraction in the smooth muscles of the cerebral arteries].
The effects of adenosine and ATP on electrogenesis and contraction in smooth muscles of the cattle basilar and middle cerebral arteries was studied with a modified sucrose gap technique. Adenosine (10(-8) - 10(-3) M) and ATP (10(-8) - 10(-6) M) induced relaxation of the muscle strips with no change in resting potential of the muscle cells. ATP (10(-5) - 10(-3) M) led to depolarization of the cell membrane followed by a hyperpolarization which was accompanied by the complex contractile reaction of muscle strips. Adenosine (10(-3) M) caused relaxation comparable to the relaxation induced by Ca++-free solution or by Mn++ ions. This suggests that extracellular Ca++ ions which participate in maintaining of the blood vessel tone enter the smooth muscle cells mainly through the stationary open adenosinesensitive Ca channels of the membrane. Ca++ ions entering the smooth muscle cells through voltage-dependent noninactivating Ca channels contribute to maintaining of cerebral arteries' basal tone. Adenosine does not affect the voltage-dependent influx of extracellular Ca++ ions through the slow noninactivating Ca channels of the cell membrane or through fast inactivating Ca channels, participating in the AP generation.
D000241:Adenosine / Q000494:pharmacology*; D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002417:Cattle; D002536:Cerebral Arteries / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004594:Electrophysiology; D066298:In Vitro Techniques; D007473:Ion Channels / Q000187:drug effects; D009119:Muscle Contraction / Q000187:drug effects*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects*
D007473:Ion Channels; D000255:Adenosine Triphosphate; D000241:Adenosine; D002118:Calcium
Deĭstvie adenozina i ATF na élektrogenez i sokrashchenie v gladkikh myshtsakh mozgovykh arteriĭ.