DECREASED SENSITIVITY OF AORTA FROM HYPERTENSIVE RATS TO VASORELAXATION BY TYRPHOSTIN

The role of protein tyrosine kinases (PTKs) in vascular smooth muscle (VSM) contraction was examined in spontaneously hypertensive rats (SHR s). Aorta from SHRs was hyperresponsive to PTK-mediated contraction re lative to normotensive Wistar-Kyoto rats (WKYs). Aorta from SHR was al so hyporesponsive to vasorelaxation by tyrphostin, a selective inhibit or of PTKs. Further, we found alterations in PTK activity in aorta fro m SHRs. PDGF stimulated PTK activity to a greater extent in the SHR. T ryphostin inhibited PDGF-induced PTK stimulation in both strains, howe ver, activity returned to basal levels in the WKY only. The results su ggest that PTKs may be involved in VSM contraction and in the developm ent of hypertension.