Blockage by yohimbine of prazosin-resistant pressor effects of adrenaline in the pithed rat.
In the pithed rat, following beta-adrenoceptor blockade, the pressor effect of adrenaline can be blocked by phentolamine or by prazosin plus yohimbine but not by prazosin or yohimbine given alone. It is concluded that adrenaline produces its pressor effect by acting on two sets of post-junctional alpha-adrenoceptors, each of which is sensitive to phentolamine, one of which is sensitive to prazosin but resistant to yohimbine and the other of which is sensitive to yohimbine but resistant to prazosin.
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D004351:Drug Resistance; D004837:Epinephrine / Q000037:antagonists & inhibitors*; D010646:Phentolamine / Q000494:pharmacology; D011224:Prazosin / Q000494:pharmacology*; D011433:Propranolol / Q000494:pharmacology; D011799:Quinazolines / Q000494:pharmacology*; D051381:Rats; D013116:Spinal Cord / Q000502:physiology; D015016:Yohimbine / Q000494:pharmacology*
D011799:Quinazolines; D015016:Yohimbine; D011433:Propranolol; D011224:Prazosin; D004837:Epinephrine; D010646:Phentolamine