. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 498 LEONARD NELSON 150- iooH c o o 50^ o Ouabain D Propranolol. 10 3M Ouabain / -« 10 ^ • Ouabain \ +Propranolol C 10 8 p Ouabain p Propranolol FIGURE 4. Interactive effects following lO-min incubation in the beta receptor blocker propranolol and the cardiac glycoside ouabain on Arbacia sperm motility in FSW. Note that the optimum concen- tration of each drug separately occurs at 10 6 A//l FSW; 10 6 A/ is also the optimum concentration for both drugs combined. Also note that in the presence of 1 mA/ ouabain, all concentratio
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 498 LEONARD NELSON 150- iooH c o o 50^ o Ouabain D Propranolol. 10 3M Ouabain / -« 10 ^ • Ouabain \ +Propranolol C 10 8 p Ouabain p Propranolol FIGURE 4. Interactive effects following lO-min incubation in the beta receptor blocker propranolol and the cardiac glycoside ouabain on Arbacia sperm motility in FSW. Note that the optimum concen- tration of each drug separately occurs at 10 6 A//l FSW; 10 6 A/ is also the optimum concentration for both drugs combined. Also note that in the presence of 1 mA/ ouabain, all concentrations of propranolol depressed motility. Ordinate. percent of control progressive motility rate; abscissa, concentrations of the drugs in negative log of molaritv. to 10 5 M quinidine after preincubation in 10 4 M or 10 6 M propranolol (Fig. 6a) show relatively little effect compared to those in 10~5 M quinidine alone. In marked contrast sperm cells exposed to 10~3M quinidine following their preincubation in 1CT4 M and 10~6 M propranolol respectively, first responded with motility increases, ranging from 160% to 200% of the rates in quinidine alone (Fig. 6b). These bursts of activity were succeeded by precipitous declines to about 50% of the control and quinidine-alone rates on prolonged exposure of the sperm in both cases. In terms of initial reaction to addition of 10"3 M quinidine to sperm cells pre- incubated in propranolol, the response appears to exceed by far that of a simple addition of the individual response rates. DISCUSSION Membrane-stabilizing agents (local anesthetics and antiarrhythmic drugs) dis- place calcium from plasma membranes. Perturbation of the calcium not only affects cell permeability (Blaustein and Goldman, 1966) but the drugs, as ligands for Ca2+- binding sites, also increase contractile tension in muscle (Bondani and Karler, 1970). Displacement of the calcium required for biological processes may enhance or dis- rupt flagellar Please
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