CHANGES IN VASCULAR WALL PRODUCTION OF PROSTACYCLIN AND THROMBOXANE-A2 IN SPONTANEOUSLY HYPERTENSIVE RATS DURING MATURATION AND THE CONCOMITANT DEVELOPMENT OF HYPERTENSION

The purpose of this study was to clarify how the metabolism of vascular prostacyclin (PGI2) and thromboxane (TX) A2 in spontaneously hypertensive rats (SHR) is involved in aging and development of hypertension. We removed the aortic walls from 5-week-old and 20 to 25-week-old SHR and age-matched Wistar Kyoto rats (WKY). At 5 weeks of age, there was no significant difference in basal and maximal (arachidonic acid 0.1 mM) 6-keto-PGF1α production between SHR and WKY, but the TXB2 generation in the SHR aortic wall was markedly enhanced as compared with that in WKY. At 20 to 25 weeks of age, the SHR aortic wall synthesized about 1.5 times more 6-keto-PGF1α in the basal condition and twice as much as in the maximal condition as did the WKY wall. However there was no significant difference in TXB2 production between SHR and WKY. Age-dependent increase of vascular 6-keto-PGF1α was greater in SHR than in WKY. Moreover, the maximal/basal 6-keto-PGF1α production ratio increased with age in SHR, but not in WKY. The synthesis of vascular TXB2 was enhanced with age in WKY, but did not change with age in SHR. These data suggest that not only the enhanced basal generation of vascular 6-keto PGF1α but also a much greater reservoir of 6-keto-PGFia synthesis in SHR was induced by both hypertension and maturity. The increased production of vascular TXB2 in young SHR may affect the development of hypertension. © 1990, The Japanese Circulation Society. All rights reserved.