Beta-adrenergic regulation of insulin secretion: evidence of tissue heterogeneity of beta-adrenergic responsiveness in the elderly.
Aging is associated with reduced beta-adrenergic receptor (beta-AR) function in several tissues. If this age effect on beta-ARs also applies to the pancreatic B-cell, it would result in relatively unopposed alpha-adrenergic inhibition of insulin secretion with adrenergic stimulation during stress states. This study compared insulin secretory responses to beta-AR stimulation (multiple IV doses of isoproterenol) with cardiac and circulating mononuclear lymphocyte (MNL) beta-AR responses in 9 healthy, non-obese young subjects, and 9 healthy, non-obese old subjects. We found no age-related decrease in the relationship between isoproterenol dose and insulin response. In contrast, the old subjects had significantly reduced heart rate responses to isoproterenol and generally lower MNL beta-AR function. We conclude that pancreatic B-cell beta-AR mediated function is not impaired in the elderly, suggesting that heterogeneity of tissue beta-AR mediated function exists in this population. Diminished pancreatic islet beta-AR mediated function does not appear to be a mechanism that predisposes healthy older individuals to the development of stress hyperglycemia.
Morrow
L A
LA
Department of Internal Medicine, University of Michigan, Ann Arbor.
Rosen
S G
SG
Halter
J B
JB
D000328:Adult; D000368:Aged; D000375:Aging / Q000378:metabolism*; D001786:Blood Glucose / Q000032:analysis; D000242:Cyclic AMP / Q000096:biosynthesis; D004837:Epinephrine / Q000097:blood; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007328:Insulin / Q000097:blood / Q000378:metabolism*; D000078790:Insulin Secretion; D007545:Isoproterenol / Q000494:pharmacology; D007963:Leukocytes, Mononuclear / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D009638:Norepinephrine / Q000097:blood; D011943:Receptors, Adrenergic, beta / Q000378:metabolism / Q000502:physiology*
D001786:Blood Glucose; D007328:Insulin; D011943:Receptors, Adrenergic, beta; D000242:Cyclic AMP; D007545:Isoproterenol; D009638:Norepinephrine; D004837:Epinephrine