| Research Abstract |
(1) Angiotensin II induced Ca transient in cultured vascular smooth muscle cells dereived from rat aorta. The response was attenuated in cells from aged rat.
(2) Aortic strip was mounted in the organ bath and the developed tension was recorded. Angiotensin II increased the force of contraction, and the response was inhibited by L-type Ca channel blocker, verapamil, Tyrosine kinase inhibitor, gen istein, con centration-depend ently inhibited the ani gotensin-induced contraction. MA kinase/ERK kinse inhibitor, PD9 8059, did not affect on the contraction, suggesting that the tyrosine kin ase, but not MAP kin ase, is involved in the angiotensin -indu ced vas ocon striction.
(3) Angiotensin-induced vasoconstriction was attenuated in the aged rat aorta. However, the level of expression of angiotensin II receptor, which was determined by competitive RT-PCR, was not altered by aging. In addition, the expression of angiotensin receptor was not reduced in the aged heart. The age- related change in response to angiotensin may be due to alteration of signaling pathway after the receptor stimulation.
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