Possible Interaction: Epinephrine and Adrenergic Alpha-1 Receptor Antagonists

“The synergistic interaction of …-5 microM) and epinephrine (0.5-2 … inhibited by alpha2-adrenoceptor blocker (yohimbine; IC50= 0.4 microM), calcium channel blockers (verapamil and diltiazem with IC50 of 10 and 48 …), PLC inhibitor (U73122; IC50=6 microM) and nitric oxide (NO) donor, SNAP (IC50=1.6 microM)).”

“We found that platelet aggregation mediated by subthreshold concentrations of histamine (1-4 microm) plus adrenaline (0.5-2 microm) is inhibited by both an alpha(2)-adrenoceptor blocker (yohimbine) and a histamine (H1) receptor antagonist (diphenhydramine).”

“The complete inhibition of the adrenaline response after blocking alpha1-adrenoceptors indicates an interaction with the beta-adrenergic pathway.”

“Thus, adrenaline inhibited HL secretion through activation of the alpha1-adrenoceptors subtype B, which have been shown to signal through Ca2+ as well as cAMP.”

“ Adrenaline stimulated glycogen degradation through both an alpha1-adrenergic mediated Ca2+ increase and a beta-adrenergic-mediated cAMP increase.”

“Melanosome aggregation induced by adrenaline and noradrenaline was partially blocked by alpha adrenergic receptor blockers and a beta receptor blocker.”

“Yohimbine alpha-adrenoceptor blocker ) suppressed the catecholamine-induced effects on VCL, and reduced strongly the hypertensive effects of adrenaline and noradrenaline and reversed that of dopamine.”

“This α‐adrenoceptor blocker also clearly attenuated the blood glucose elevation observed on infusing adrenaline at 0.3 μg kg−1 min−1.”

“The anti-amnestic effect of epinephrine , but not that of ACTH or beta-endorphin, was also antagonized by the alpha 1-adrenergic receptor blocker , prazosin HC1 (2.0 mg/kg).”