title: Aortic responses to vanadate: independence from (Na,K)-ATPase and comparison of Dahl salt-sensitive and salt-resistant rats.
abstract: Vanadate at doses from 10(-4.5) to 10(-3) M caused a dose-dependent contraction of the rat aorta in vitro. Aortas of Dahl salt-hypertension sensitive (S) rats responded to vanadate with a greater contraction than Dahl salt-hypertension resistant (R) rats. In contrast, S and R aortic responses to depolarization with potassium were equal, and responses to norepinephrine were less in S than R. The mechanism by which vanadate causes the aortic response was studied in S rats. In aortic smooth muscle sodium-loaded by exposure to low potassium media followed by a norepinephrine-induced contraction, a relaxation induced with 5 mM potassium was not influenced by 10(-3) M vanadate. Since this potassium-induced relaxation is known to be a reflection of (NaK)-ATPase activity, these data show that vanadate (up to 10(-3) M does not inhibit (Na,K)-ATPase in intact smooth muscle cells although it is a known potent inhibitor of (Na,K)-ATPase in isolated cell membrane preparations. Response to vanadate was not changed by alpha-blockade with phentolamine or by blocking (Na,K)-ATPase with ouabain. Vanadate contraction was blocked by 4,4'-diisothiocyano-2,2'-disulfonic acid stilbene, a known inhibitor of anion transport, suggesting that vanadate anions must enter smooth muscle cells to induce contraction.
mesh_terms: D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000818:Animals; D001011:Aorta / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D006973:Hypertension / Q000139:chemically induced / Q000503:physiopathology*; D066298:In Vitro Techniques; D009119:Muscle Contraction / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000201:enzymology; D051381:Rats; D012965:Sodium Chloride / Q000494:pharmacology*; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors*; D014638:Vanadates; D014639:Vanadium / Q000494:pharmacology*
chemical_list: D000317:Adrenergic alpha-Antagonists; D014639:Vanadium; D014638:Vanadates; D012965:Sodium Chloride; D000254:Sodium-Potassium-Exchanging ATPase