Beta 2-adrenoceptor induced increase of plasma insulin levels in man: evidence of direct and indirect B-cell stimulation and liver effects.
Beta 2-Adrenoceptor stimulation is known to increase plasma levels of insulin in man. To study the mechanism behind this increase, plasma insulin, plasma C-peptide, and blood glucose responses to the beta 2-adrenoceptor agonist terbutaline were investigated in healthy humans. Terbutaline (125 micrograms i.v.) induced an increase in plasma levels of C-peptide from 0.68 +/- 0.11-0.90 +/- 0.14 nmol/l after 2 min (p less than 0.05) (n = 10). Likewise, plasma insulin concentrations increased, from 0.16 +/- 0.05-0.30 +/- 0.08 nmol/l (p less than 0.02). 20 min after terbutaline injection, plasma levels of C-peptide were 0.98 +/- 0.26 nmol/l and of insulin were 0.21 +/- 0.05 nmol/l. Calculations of the minute to minute increase of plasma levels of C-peptide and insulin during the 20 min after terbutaline injection, revealed that plasma insulin increased during the first 2 min by 59 +/- 8% of the increase of plasma C-peptide, and during the third and fourth min by 44 +/- 12% of the increase of plasma C-peptide; the difference being the liver extraction of insulin. In contrast, during min 4-10 after terbutaline injection, plasma insulin levels increased more than did plasma C-peptide levels, indicating that terbutaline inhibits the liver extraction of insulin. Blood glucose levels did not change during the first 4 min after terbutaline injection. During min 6-10 after terbutaline administration, blood glucose increased, from 4.94 +/- 0.24-5.42 +/- 0.25 mmol/l (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)
D000328:Adult; D001786:Blood Glucose / Q000032:analysis; D002096:C-Peptide / Q000097:blood; D006801:Humans; D007328:Insulin / Q000097:blood*; D007515:Islets of Langerhans / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D008875:Middle Aged; D011943:Receptors, Adrenergic, beta / Q000187:drug effects / Q000502:physiology*; D013726:Terbutaline / Q000494:pharmacology
D001786:Blood Glucose; D002096:C-Peptide; D007328:Insulin; D011943:Receptors, Adrenergic, beta; D013726:Terbutaline