PubMed · 29013
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A A El-Etr, S N Glisson. 1978. Alpha-adrenergic blocking agents.. https://doi.org/10.1097/00004311-197816020-00011
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BACKGROUND: Coronary vasoconstriction has been described after uncomplicated percutaneous transluminal coronary angioplasty (PTCA). However, it is still unknown whether this phenomenon is limited to coronary circulation. The present study was planned to assess the effects of a successful PTCA on forearm blood flow (FBF) and resistance. The role of alpha-adrenoceptors and calcium antagonist agents on PTCA-induced limb blood flow changes was also investigated. METHODS AND RESULTS: We prospectively studied 37 patients scheduled for elective single PTCA of the left anterior descending coronary artery. All patients had evidence of exercise-induced myocardial ischemia. All vasoactive drugs were withdrawn for at least 48 hours before the study. FBF was measured by calibrated venous occlusion plethysmography. A significant reduction of FBF was observed at 1, 5, and 15 minutes after PTCA (from 3.7 +/- 1.2 to 2.7 +/- 1.5, 3.0 +/- 1.6, and 2.9 +/- 1.9 mL/100 mL tissue per minute, respectively; all P < .05 versus baseline). Vascular forearm resistance also increased at 1, 5, and 15 minutes after PTCA (from 27 +/- 8 to 42 +/- 16, 37 +/- 10, and 43 +/- 19 U, respectively; all P < .05 versus baseline). Phentolamine (12 microgram.kg-1.min-1, n = 7) or verapamil (3.5 micrograms.kg-1.min-1, n = 7) also was infused intra-arterially. PTCA-induced forearm vasoconstriction was completely abolished by pretreatment with regional infusion of phentolamine or verapamil. CONCLUSIONS: After an uncomplicated PTCA of the left anterior descending coronary artery, a reduction in FBF and an increase in forearm vascular resistance were observed. This peripheral vasoconstrictive response was probably due to alpha-adrenergic stimulation and was abolished by intra-arterial infusion of calcium antagonist agents.
The mechanism of the positive inotropic effect of prostacyclin (PGI2) (2.6 x 10(-6) mol/l) on the isolated right ventricle of rat heart was studied. Our results show that the positive inotropic effect of prostacyclin is produced indirectly through beta adrenoceptors and slow Ca2+ channels, because blockade of slow Ca2+ channels with verapamil (10(-6) mol/l) and beta adrenoceptors with propranolol (10(-6) mol/l) abolishes this effect. Alpha adrenoceptors do not mediate the action of PGI2.