Possible Interaction: Epinephrine and Phentolamine

“The α-adrenoceptor blocker, phentolamine , resulted in the ‘disinhibition’ of the femoral ATBF response to adrenaline (p < 0.001).Conclusions/interpretationFatty acids, once stored in femoral adipose tissue, are not readily released upon adrenergic stimulation.”

“The proposed mechanism is that phentolamine , an alpha-adrenergic antagonist, blocks the vasoconstriction associated with the epinephrine used in dental anesthetic formulations, thus enhancing the systemic absorption of the local anesthetic from the injection site.”

“When epinephrine was infused in combination with 100 microM phentolamine (a nonselective alpha-AR antagonist), the inhibition of epinephrine (10 microM)-induced lipolysis was only of 19 and 40% during hours 3 and 6 of the clamp, respectively.”

“ Phentolamine enhanced the beta-adrenergic vasodilator responses to adrenaline , as both the decrease in diastolic blood pressure and the reflexogenic increase in heart rate were enhanced (both P less than 0.01).”

“When phentolamine preceded epinephrine infusion, a more marked rise in FFA occurred than with either drug alone.”

“Pretreatment with phentolamine , an alpha adrenergic antagonist, blocked the release of PA by epinephrine while pretreatment with the beta blocker propranolol had no effect.”

“This stimulation of GTPase activity by epinephrine is prevented in the presence of the alpha-adrenergic antagonist, phentolamine , which indicates that a functional reconstitution of the alpha 2AR and Ni has been established.”

“Noradrenaline, adrenaline and phenylephrine produced increases in frequency and tension of the contractions which were reversed to decreases or depressed by phentolamine.”

“On the contrary, phentolamine (1.25--30 micrometer) potentiated the inhibitory effect of epinephrine on rat platelets and unmasked an inhibitory effect on human platelets.”

“2 Since phentolamine or phenoxybenzamine inhibited the contractions induced by adrenaline or noradrenaline in the presence of oxprenolol, it is assumed that the contractions are caused by stimulation of excitatory α‐adrenoceptors.”