Some examples of the effect of asymmetric nitrogen atoms on physiological activity / by P.P. Laidlaw.

  • Laidlaw, Patrick Playfair, 1881-1940.
Date:
[1913]
Catalogue details

Licence: In copyright

Credit: Some examples of the effect of asymmetric nitrogen atoms on physiological activity / by P.P. Laidlaw. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

    5/12 (page 463)
    may say that /3 canadine methochloride is about ten times as at tive as the a salt. TABLE i Frogs’ average weight 20 grams /3 Z-CANADINE METHOCHLORIDE Dose Effect mgm. 4.0 Complete paralysis in 7 min. 2.5 Complete paralysis in 8 min. 1.0 Complete paralysis in 10 min. 0.25 Nearly complete paralysis in 50 min. 0.10 Partial paralysis in 50 min. a /-CANADINE METHOCHLORIDE [ Dose Effect mgm. 4.0 Complete paralysis in 30 min 2.5 Nearly complete paralysis in 45 min. 1.0 Partial paralysis in 45 min. It appeared unlikely that an accurate comparison could be made hy this method. Variations in individual frogs, apart from weight, and the difficulty in gauging the degree of paraly- sis, make comparisons difficult. More accurate comparison is obtained by the following method. The hind legs of a frog were perfused with Ringer’s solution through the aorta just above the bifurcation into the iliac arteries. One sciatic nerve was stim- ulated at intervals of ten seconds, with single maximal induction shocks, and the height of contraction of the gastrocnemius muscle was recorded. The opposite limb was then excluded from cir- culation by a small clip on the iliac artery and Ringer’s solution containing a known dilution of alkaloid was perfused through the stimulated limb. The height of contractions slowly diminishes as perfusion is continued and a curve of the onset of paralysis for a given dilution is thus obtained. Plain Ringer’s solution is then substituted to study the rate of recovery. The other leg is then treated in a precisely similar manner, except that a known dilution of the other isomer is perfused through it. In this way a fairly accurate comparison of activities is obtained (see fig. 1 and 2.) The perfusion pressure was kept high in order to ex- clude effects of differences in perfusion rate and was, of course, the same for right and left legs.