Effects of cocaine or denervation on responses of isolated strips of cat spleen to (‐)‐noradrenaline and (‐)‐isoprenaline

Abstract

1 A study has been made of the effects of cocaine and sympathetic denervation on responses of the cat spleen to (–)-noradrenaline and (–)-isoprenaline. 2 Responses of isolated strips of spleen capsule to (–)-noradrenaline or to (–)-isoprenaline were not affected by reserpine-pretreatment. 3 In adult cats, cocaine (1 and 10 μg/ml) or denervation produced a shift to the left of dose-response curves to (–)-noradrenaline, whereas they failed to modify dose-response curves to (–)-isoprenaline. 4 There was an increase in the maximum development of tension to (–)-noradrenaline after denervation or in the presence of cocaine (10 μg/ml). These procedures did not increase the maximal responses to (–)-isoprenaline. 5 Cocaine (10 μg/ml) did not affect dose-response curves to (–)-noradrenaline or (–)-isoprenaline in the denervated spleen. 6 In the kitten spleen, cocaine (1 and 10 μg/ml) produced a shift to the left of dose-response curves to (–)-noradrenaline both in untreated and in reserpine-pretreated tissues. 7 There was a small shift to the left in dose-response curves to (–)-isoprenaline in the presence of cocaine in the untreated but not in the reserpine-pretreated kitten spleen. 8 It is concluded that the potentiation of responses to (–)-noradrenaline in the cat's spleen is due to a prejunctional effect of cocaine.