M. Iwase et al., The pancreatic islets in spontaneously hypertensive rats: islet blood flowand insulin production, EUR J ENDOC, 144(2), 2001, pp. 169-178
The aim of the study was to investigate if hypertension affects pancreatic
islet blood flow and endocrine function. For this purpose. spontaneously hy
pertensive rats (SHR) were compared with normotensive control Wistar-Kyoto
rats (WKY). Both islet size and islet cell replication in 4-month-old SHR w
as increased compared with WKY. The (pro)insulin biosynthesis was reduced i
n islets isolated from SHR, whereas the insulin content was unchanged. A hy
perinsulinemic 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 and 1-year-old SHR. In 4-month-old anim
als, islet blood flow was unaffected by administration of enalaprilate and
prazosin in both strains, but was markedly decreased by the administration
of N-G-methyl-L-argimine. It was concluded that the islets of SHR have a de
creased insulin production in vitro and a decreased islet blood perfusion.
The reasons for this are likely to be multifactorial. Because SHR maintaine
d an essentially normal glucose tolerance, an adaptation of the beta -cells
to the metabolic and hemodynamic changes imposed by hypertension occurred.