Peculiar long-term effects of catecholamines and their blockers in rats on insulin, glucose and pancreas.
To be able to study the long-term effects of moderately enhanced catecholamine levels in rats, we developed subcutaneously implantable retard systems, granting a linear output of various agents throughout the test time. Adrenaline application leads to hyperglycemia without elevation of serum immune-reactive-insulin (IRI) during 20 h of uninterrupted adrenaline (A) action. This we call an A-induced diabetes like reaction. It could be completely abolished by simultaneous application of low phentolamine (Regitin) doses. Simultaneous application of propranolol (P) gradually diminished blood glucose levels from about 200 mg/dl after 6 h to 120 mg/dl after 20 h. Since here insulin levels are uniformly low, decline of blood glucose could not be due to enhanced insulin-action. The moderate hyperglycemia after 6 h isoprenaline (ISO)-treatment alone goes with a hyperinsulinemia at the same time. Obviously this hyperinsulinemia cannot cope with the increased blood glucose probably due to enhanced liver-glycogenolysis by intact alpha-action. Later on insulin--despite of beta-action on pancreas--declines strictly proportional with diminishing blood-glucose-levels. A comparison between the action of catecholamines and their blockers showed that alpha-blockers tend to diminish blood glucose levels by two independent ways, namely by the inhibitory action on pancreas and the inhibitory action on liver glycogenolysis.
D000818:Animals; D001786:Blood Glucose / Q000032:analysis*; D002395:Catecholamines / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D007328:Insulin / Q000097:blood*; D010179:Pancreas / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D013997:Time Factors
D001786:Blood Glucose; D002395:Catecholamines; D007328:Insulin