Effect of modulators of protein tyrosine kinase activity on gender-related differences in vascular reactivity at...

We used the isolated-muscle-bath technique to examine the effect of protein tyrosine kinase (PTK) and protein tyrosine phosphatase (PTP) inhibitors on the response of rings of tail artery from male and female rats to cooling and reduced temperature in the absence and presence of two PTK-dependent (clonidine and serotonin) and one PTK-independent (phenylephrine, PE) agonists. At 37 degrees C, reactivity to clonidine, serotonin, and PE was the same in tail artery from female and male rats. At 25 degrees C, reactivity to clonidine and serotonin, but not PE, was greater in tail artery from female rats compared with those from male rats. Sodium orthovanadate (SOV) eliminated the gender-related difference in the contractile effect of clonidine and serotonin at 25 degrees C. The sensitivity to relaxation by genistein was considerably greater for clonidine and serotonin at both temperatures as compared with PE. At 25 degrees C the sensitivity to genistein was greater for the clonidine and serotonin-contracted rings from female rats. In the presence of SOV, temperature reduction led to contraction of rat-tail artery. This effect was greater in rings from female rats. Our results strongly implicate differences in the activity of the PTK transduction pathway as the cause of the observed gender-related differences in agonist-mediated contraction at 25 degrees C and in cold-induced vasoconstriction.