Angiotensin II effect on 22Na+ transport in vascular smooth muscle cells.
It is well established that angiotensin II (AII) rapidly increases free cytosolic Ca2+ in vascular smooth muscle cells (VSMCs). Several studies have indicated that the hormone also plays a role in Na+-K+ regulation of these cells. In this study, we explored the mechanism of AII effect on 22Na+ transport in cultured rat VSMCs. The 22Na+ washout from these cells was described by three exponents with exponential factors k1 greater than k2 greater than k3. In 1.8 mM Ca2+ medium, AII (10(-9)-10(-6) M) increased (in a dose response manner) the k1 value, and consequently the initial washout rate constant (kei) for the isotope. AII had no effect on kei in Ca2+-deficient medium or in the presence of ouabain. Amiloride (10(-3) M) and verapamil (10(-5) M) abolished the AII induced increase in kei. These findings are consistent with angiotensin II stimulation of an amiloride-sensitive Na+ transport, which is likely to represent the Na+/H+ antiport. In cultured VSMCs, the sustained stimulation by AII of this transport system requires the presence of extracellular Ca2+ and its influx into these cells.
D000584:Amiloride / Q000494:pharmacology; D000804:Angiotensin II / Q000494:pharmacology*; D000818:Animals; D002478:Cells, Cultured; D004347:Drug Interactions; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000378:metabolism; D010042:Ouabain / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D012964:Sodium / Q000493:pharmacokinetics*; D012979:Sodium Radioisotopes; D014700:Verapamil / Q000494:pharmacology
D012979:Sodium Radioisotopes; D000804:Angiotensin II; D010042:Ouabain; D000584:Amiloride; D012964:Sodium; D014700:Verapamil