Vascular relaxation response to hydrogen peroxide is impaired in hypertension

1. In phenylephrine (1 microm)-precontracted rat superior mesenteric arteries (MA), hydrogen peroxide (H(2)O(2), 0.3 and 1 mm) caused a biphasic response: a transient contraction followed by a relaxation. In the presence of thromboxane A(2)/prostaglandin H(2) (TP) receptor antagonist (SQ 29548), the contractile component of the biphasic response was abolished. The relaxation response to H(2)O(2) was smaller in spontaneously hypertensive rats …