Binding of 3H-norepinephrine to receptors of pancreatic islets isolated from neonatal and adult rats.
Binding of 3H-norepinephrine to receptors and insulin release from pancreatic islets isolated from newborns and adult rats were investigated. In the presence of norepinephrine at the concentration of 2.4 x 10(-8) mol/l adults islets bound 0.37 +/- 0.11 fmol of norepinephrine per micrograms of islet protein while neonatal islets bound 0.25 +/- 0.08 fmol/micrograms. When norepinephrine concentration was raised to 10(-5) mol/l the amount of bound norepinephrine increased up to 22.66 +/- 8.7 fmol/micrograms and 14.20 +/- 5.36 fmol/micrograms for both examined groups, respectively. Addition of 5 x 10(-4) mol/l of phentolamine to the incubation medium induced 74% and 70% decrease of bound norepinephrine to adult and neonatal islets, respectively. At similar range of concentrations both norepinephrine and phentolamine modified the rate of insulin secretion and caused changes in binding of 3H-norepinephrine. There were no differences between the binding of norepinephrine to neonatal and adult islets. This may suggest that adrenergic system may play greater role in the regulation of insulin release from neonatal than from adult islets.
Gembal
M
M
Department of Endocrinology, Institute of Obstetrics and Gynecology, Medical Academy in Gdańsk, Poland.
Wójcikowski
C
C
D000818:Animals; D000831:Animals, Newborn; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000502:physiology*; D009638:Norepinephrine / Q000502:physiology*; D010646:Phentolamine / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D011942:Receptors, Adrenergic, alpha / Q000378:metabolism*
D007328:Insulin; D011942:Receptors, Adrenergic, alpha; D009638:Norepinephrine; D010646:Phentolamine