PHARMACOLOGY

 FROG S RECTUS ABDOMINIS MUSCLE PREPARATION ::

A frog is pithed and laid on its back on a cork covered board to which it is pinned The skin covering the abdomen is cut away and the rectus abdominis muscle of one side is dissected from the pelvic girdle to its insertion in the cartilage of the pectoral girdle The muscle is then pinned to the cork by four pins to keep its normal length while a thread is sewn through each end 

    It is then mounted in the organ bath connaining frogs Ringer solution which contains : NaCI 6.5 gm : KCI 0.29 gm CaCI2 0.24 gm NaHCO3 0.4 gm : glucose 1.5 gm and distilled water 2000 ml Oxygenation is carried out to keep the tissue alive The muscle is stabilized for 30-45 min in order to get critical quantitative response The responses are recorded using isotonic frontal writing lever with 1 G tension 

        Two similar contractions with the same concentration of acetylcholine are obtained Three doses of the standard sample and one intermediate dose of the test sample are selected and the reduction in height of contraction induced by acetylcholine is noted down 

    Acetylcholine contraction is recorded on slow moving drum for 90 sec d-Tubocurarine is allowed to act for 30 sec The percentage reduction at each dose levels is calculated and log dose response curve of the standard drug is plotted A linear response will be obtained The potency of test sample is calculated from the standard curve