Role of blood pressure in regulating Na+/H+ exchange in vascular smooth muscle

Na + /H + exchange differs kinetically in mesenteric arteries from spontaneously hypertensive rats (SHR). Both the maximal transport rate and the sensitivity to [H + ]; are greater in SHR than in Wistar Kyoto (WKY) rats. Kinetic changes are not seen in prehypertensive SHR or in SHR rendered normotensive by captopril therapy. Thus, blood pressure affects the properties of Na + /H + exchange in SHR. To determine whether elevated pressure would have similar effects on the WKY transporter, WKY rats were rendered hypertensive by treatment with deoxycorticosterone acetate (DOCA). Mesenteric arteries from these animals were loaded with the pH-sensitive dye BCECF and Na + /H + exchange activity was assessed by measuring the Na o -dependent, dimethyl amiloride-sensitive recovery of intracellular pH after acid loading