The pancreatic islets in spontaneously hypertensive rats: Islet blood flow and insulin production

Abstract

The aim of the study was to investigate if hypertension affects pancreatic islet blood flow and endocrine function. For this purpose, spontaneously hypertensive arts (SHR) were compared with normotensive control Wistar-Kyoto rats (WKY). Both islet size and islet cell replication in 4-month-old SHR was increased compared with WKY. The (pro)insulin biosynthesis was reduced in islets isolated form SHR, whereas the insulin content was unchanged. A hyperinsulinemic response to glucose in vivo was observed in 4- and 12-month-old SHR. Pancreatic blood flow, measured using a microsphere technique, was lower in SHR than in WKY in rats aged 5 weeks, 4 months or 1 year. Islet blood flow was lower in 4-month-old SHR. In 4-month-old animals, islet blood flow was unaffected by administration of enalaprilate and prazosin in both strains, but was markedly decreased by the administration of NG-methyl-L-arginine. It was concluded that the islet of SHR have a decreased insulin production in vitro and a decreased islet blood perfusion. The reasons for this are likely to be multifactorial. Because SHR maintained an essentially normally glucose tolerance, an adaptation of the β-cells to be metabolic and hemodynamic changes imposed by hypertension occurred.