Possible Interaction: Adenosine and Glucagon

“ABSTRACT The glycemic response to glucagon is activated via hepatic adenosine 3′,5′-monophosphate (cyclic AMP), and the subsequent urinary cyclic AMP response to glucagon has previously been found to be of hepatic origin.”

“Though exogenous application of adenosine has been demonstrated to stimulate glucagon release and inhibit insulin release, the physiological significance of this pathway has been unclear.”

“Vasomodulation resulted in significant decreases in normalized tumor perfusion ratio: 66.22% ± 24.57 (P < .01) with glucagon, 71.45% ± 22.72 (P < .01) with adenosine, and 74.98% ± 16.58 (P < .01) with glucagon plus adenosine.”

“ Adenosine also inhibited glucagon release while ATP was stimulatory.”

“ Adenosine inhibited the glucagon mediated increase in cAMP.”

“Superimposition of glucagon to adenosine caused further vasodilation, and the autoregulatory efficiency was completely attenuated.”

“Previous studies have shown that adenosine , by activation of purinergic A2-receptors, stimulates glucagon secretion and increases vascular flow rate in isolated perfused pancreases from nondiabetic rats.”

“Whereas, in normal rats, adenosine (1.65 μM) induced a 200% increase in glucagon output and a 25% rise in the pancreatic vascular flow rate, in rats diabetic for 5–6 wk, this nucleoside was ineffective on glucagon secretion, and its vasodilatory effect was strongly reduced.”

“Previous studies from our … showed 1) that adenosine (1.65 microM), a substance released by tissues in energy-deficient states, stimulated glucagon secretion by activation of A2 purinergic receptors, and 2) that this effect was potentiated by a low substimulating concentration of epinephrine through activation of alpha-adrenergic receptors.”

“In vivo adenosine administration altered the secretion of hormones by the islets of Langerhans (increased the release of glucagon and decreased the secretion of insulin) but this was only clearly observable under stimulated conditions.”

“Conversely, upon removal of adenosine , addition of Rs ligands such as isoproterenol, adrenocorticotropic hormone, or glucagon strongly inhibited transport (approximately 50%) and stimulated kinase activity.”