title: Vasopressin induced rhythmic activity in rat basilar artery.
abstract: The effects of vasopressin on membrane potential and tension were studied in isolated segments of basilar arteries from the University of Iowa colonies of normotensive inbred Kyoto-Wistar rats (WKY) and stroke-prone spontaneously hypertensive rats (SP-SHR). In the presence of vasopressin (0.01-0.3 IU/ml), basilar arteries from WKY, but not from SP-SHR, developed rhythmic contractions. These contractions were recorded in 13 of 14 WKY basilar arteries, were unaffected by pretreatment with 6-hydroxydopamine, and were characterized by 20-100 dyne oscillations in tension, occurring 1-3 cycles/min, and superimposed on the vasopressin-induced contraction (averaging 60 dynes at 0.01 IU/ml or 160 dynes at 0.3 IU/ml). However, resting membrane potentials were not different in SP-SHR vs. WKY at 37 degrees C, and both strains showed about the same (11 mV) depolarization by 0.1 IU/ml of vasopressin. The rhythmic contractions were enhanced by K+-free solution, and abolished in the presence of high K+ solution (30 mM), suggesting that active Na+-K+ transport may be involved in modulating the rhythmic activity. These findings are consistent with the hypothesis that the vasopressin-induced rhythmic contractions in WKY basilar arteries are at least partly dependent on a reduced activity of electrogenic Na+-K+ active transport in WKY as compared to SP-SHR.
mesh_terms: D000818:Animals; D001488:Basilar Artery / Q000187:drug effects* / Q000502:physiology; D001698:Biomedical Engineering; D066298:In Vitro Techniques; D008236:Lypressin / Q000494:pharmacology*; D008564:Membrane Potentials / Q000187:drug effects; D011188:Potassium / Q000378:metabolism / Q000494:pharmacology; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D012964:Sodium / Q000378:metabolism; D014661:Vasoconstriction / Q000187:drug effects*
chemical_list: D008236:Lypressin; D012964:Sodium; D011188:Potassium