[Effects of adrenomedullin on secretory function of pancreatic islet in spontaneously hypertensive rat in vitro].
OBJECTIVE
To study the effects of adrenomedullin (AM) on secretory function of pancreatic islet in spontaneously hypertensive rat (SHR) and Wistar-kyoto (WKY) rat.


METHODS
Ten SHRs (test group) and ten WKY rats (control group) were used. The pancreatic islets isolated from SHR and WKY rats were put into 12-well plates. The islets were incubated in RPMI-1640 medium containing 2.8 mmol/L glucose (low glucose group) for 45 minutes. The second incubation was performed in RPMI-1640 medium containing 11.1 mmol/L glucose (high glucose group) and various concentrations of AM (0, 10(-8), 10(-7), 10(-6) mol/L, respectively) for 24 hours. The supernatants from both incubations were tested by RIA for insulin and glucagon.


RESULTS
The insulin concentrations in supernatants collected from the islets of WKY rats incubated in high glucose and various concentrations of AM for 24 hours were decreased in the dose dependent manner. When the islets of WKY rats and SHR were incubated in AM of high concentration (10(-6) mol/L), the insulin concentrations in supernatants decreased significantly. When the islets of SHR were incubated in high glucose and various concentrations of AM for 24 hours, the glucagon concentrations in supernatants were not significantly different.


CONCLUSIONS
The above results demonstrate that AM inhibits insulin secretion in beta cell of islets of WKY rats in dose dependent manner, that AM that AM of high concentration inhibits insulin secretion in beta cell of islets of SHR, and that AM has no influence on the function of alpha cell of islets. These suggest that AM may contribute to the impaired beta cell function during the development of diabetes mellitus.
Chen
Chuanqi
C
Department of Endocrinology, West China Hospital, Sichuan University, Chengdu 610041, China.
Tong
Nanwei
N
Zhang
Wenyi
W
D053607:Adrenomedullin; D000818:Animals; D004305:Dose-Response Relationship, Drug; D005260:Female; D005934:Glucagon / Q000032:analysis / Q000378:metabolism; D006973:Hypertension / Q000503:physiopathology*; D007328:Insulin / Q000032:analysis / Q000378:metabolism*; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000378:metabolism*; D008297:Male; D010455:Peptides / Q000494:pharmacology*; D011863:Radioimmunoassay; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY
D007328:Insulin; D010455:Peptides; D053607:Adrenomedullin; D005934:Glucagon