Responses of isolated bronchial muscle to ganglionically active drugs / by D.F. Hawkins and W.D.M. Paton.

  • Hawkins, D. F. (Denis Frank)
Date:
[1958?]
Catalogue details

Licence: In copyright

Credit: Responses of isolated bronchial muscle to ganglionically active drugs / by D.F. Hawkins and W.D.M. Paton. Source: Wellcome Collection.

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    potentiation of the response to nicotine by known adrenaline potentiators. This proved to be the case. For example, with cocaine the lowest concentration with which we were able reproducibly to potentiate adrenaline responses on the trachea was about 100 /xg/ml., whereas this local anaesthetic will often antagonize the nicotine response in concentrations as low as 0-02 gg/ml. Rosa & McDowall (1951) reported that ascorbic acid increases the response of isolated human bronchial muscle to adrenaline. We were unable to confirm 6-0 5-0 Nice stine Ad re Norad r naline ■enaline Isopre aaline Nice atine Ad re Noradr laline enaline Isopre rnaline \ IpA^ 4 4 c < J I p At -i ) IT-. . i ► » 5 i ] > » < c leMj P- PA2 —^ i i ) > . » c PA2-j 3 3 / pAl » < » /l 3 C i i c ► < < 1 5 PA2 1 3 ) ) > 3 } 1 Ergotamine Dihydroergotamine Fig. 6. Diagram of results of experiments to estimate pA2 of ergotamine and dihydroergotamine against nicotine, adrenaline, noradrenaline, and isoprenaline. 0> >pA2; Q, = pA2 approx.; •, <pA2; P, potentiation. Table 2. pA2 values and relative potencies of sympatholytics in the antagonism of bronchodilator effects on the guinea-pig trachea Nicotine Adrenaline Noradrenaline Isoprenaline PA2 Ergotamine 5-8 6-0 (4-9) 6*1 Dihydroergotamine 6-3 6-3 (4-8) 6-3 Relative potency Ergotamine 60 100 (8) 130 Dihydroergotamine 200 200 (6) 200 Ergotamine versus adrenaline = 100. this on guinea-pig trachea, and the action of ascorbic acid on the nicotine response was difficult to assess, because irregular changes in the base line followed the addition of ascorbic acid to the bath. Other drugs. Atropine in concentrations from 1 to 100 /xg/ml. reduced the bronchodilator nicotine response without affecting the response to adrenaline or noradrenaline. The minimum concentration of atropine found to be active in this respect was more than one hundred times that required to reduce an acetylcholine contraction of the trachea. Mepyramine had a rather irregular influence on the response to adrenaline and noradrenaline, sometimes poten¬ tiating the action of the latter. It reduced the nicotine response. Tolazoline,