Regional blood flow in canine brain during nicotine infusion: effect of autonomic blocking drugs

G J Crystal, H F Downey, T P Adkins, F A Bashour
1983 Stroke  
Radioactive microspheres (15 /JL) were used to measure regional cerebral blood flow during intravenous infusion of nicotine (36 ^ig/kg/min) in anesthetized, open chest dogs. Experiments were con ducted with uncontrolled mean aortic pressure and intact autonomic receptors (Series I; n = 9), and in four groups of dogs with mean aortic pressure held constant (Series II); 1) with intact autonomic receptors (n = 6), 2) after beta adrenergic blockade (n = 8), 3) after alpha and beta adrenergic
more » ... a adrenergic blockade (n = 6), 4) after alpha and beta adrenergic and cholinergic blockade (n = 4). In Series I, nicotine raised mean aortic pressure ( + 72%) and increased flow in cerebral cortex ( + 67%), cerebellum ( + 38%), pons ( + 46%), medulla ( + 39%), and spinal cord ( + 48%). In all regions, but cortex, increases in vascular resistance limited nicotine-induced increases in flow. In Series II, nicotine changed flow only in cortex. Without blockade, nicotine increased cortical flow ( + 38%); but beta blockade abolished this increase in flow. After alpha and beta blockade nicotine again raised cortical flow ( + 29%), and additional cholinergic blockade had no effect on this response. It is concluded that nicotine causes predominant beta receptor mediated vasodilation in cerebral cortex, although it also activates alpha (vasoconstrictor) receptors and a nonadrenergic, non-cholinergic vasodilator mechanism in this region of brain. The present experiments were carried out in a painless manner with the guidelines of the Ethics Committee of the American Heart Associ ation regarding animal experimentation. 0.05, effect of nicotine. Values are mean ± SE in 9 dogs. Cerebral Cerebellum Pons Medulla Spinal Cortex Cord FIGURE 1. Effect of nicotine on regional cerebral vascular resistance with uncontrolled aortic pressure and intact auto nomic receptors (n = 9). by guest on July 19, 2018 http://stroke.ahajournals.org/ Downloaded from References 1. Downey HF, Bashour CA, Boutros IS, Bashour FA, Parker PE: Regional myocardial blood flow during nicotine infusion: Effects of beta adrenergic blockade and acute coronary artery occlusion. J
doi:10.1161/01.str.14.6.941 pmid:6140781 fatcat:2eg2hpdufnggrej3sjx5mrpyzy