Phosphoinositide Metabolism and Aging in Aorta from SHR and WKY Rats: Effects of Endothelin-1 and Noradrenaline

Inositol phosphate formation in aortic rings from SHR and WKY rats of different ages (6, 14, and 40 weeks) was examined. Both basal and agonist (noradrenaline and endothelin-1) stimulated levels of inositol phosphates were studied. No differences in basal levels of inositol phosphate formation were observed between SHR and WKY nor were differences in agonist stimulated levels found in 6 week old animals. However, at 14 and 40 weeks both noradrenaline and endothelin-1 stimulated levels were reduced in SHR compared to WKY. Both endothelin and noradrenaline stimulated inositol phosphate formation decreased with age in SHR. In WKY there was a decrease in endothelin but not noradrenaline stimulated levels with age. Age related decreases were consistently greater in SHR than WKY. Thus, both age and rat strain modulated agonist stimulated inositol phosphate formation.