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SCHRECK ET AL.: ELECTROSHOCK: PHYSIOLOGICAL RESPONSES BY TROUT 79 120 _ ^ Shocked W 100 ~ Control N ~ 80 I 4 60 v~ E v 40 0 ~ 20 R9 0 I 3 6 c ° 20 +~ 4 4 0 !5 O ~ 10 4 A E ~ 5 .. 0 ,- v 0 I 3 6 J Time Atfer Shock (h) Frc. 1. Average concentrations (mg/ I00 ml) of glucose (vertical line at top of each bar shows s>r) and lactate (vertical line at the top of each bar shows range) levels in plasma of electroshocked and un- shocked rainbow trout (Salmo Kairdneri). Numbers of determinations are shown above each bar. Lactic acid levels in the blood doubled im- mediately after the fish were shocked and re- mained high for 1 h (Fig. 1) . By 3 h post treat- ment, however, concentrations were not signifi- cantly different from control levels. Variances were heterogenous. Lactate did not vary signifi- cantly between the control fish sampled at the time of shocking (7C = 8.5 mg/ 100 ml) and 6 h later (X = 10.0 mg/100 ml). Two control groups did not differ in circulating corticoids, average levels were 33.7-±- 8.7 ng/ml sE at time 0 and 24.7 ~- 8.0 ng/m1 sF 6 h later. The concentrations of corticoids in the shocked fish were extremely high but showed large, heterogenous variability among individuals in the same treatment. So that corticoids could be ex- pressed in definite units of measurement such as nanograms per milliliter, we assayed various con- centrations of plasma from treated fish to obtain values that fall on the sensitive portions of the standard curves made for each assay. Errors would he unequally magnified when large, varying multiplication factors were employed to express all of the data on a per milliliter basis. The data in Fig. 2 are based on identical volumes of plasma extracted for corticoids to ensure that the evalua- tion of the effects of electroshock would be conser- vative. To avoid the multiplication problem men- tioned, we did not. convert the data to direct units of measurement. These "indices" of corticoid con- centration indicated that corticoids reacted to shocking stress with an immediate, significant in- crease and remained high for at least 6 h. The magnitude of this increase can be appreciated by considering the scale (percentage bound) em- ployed. A level of 0 ng/ml would be rated "1.00% bound." The fact that corticoids in shocked fish are about 40°Jo bound indicates that their corticoid concentrations were higher than 80 ng/ml. The above calculations were based on sample volumes of 0.05 ml. Absolute values re- flecting multiplication error based on determina- tions from 0.02 ml plasma indicate that the mean levels (nanograms per milliliter; sE in paren- theses) were at ]east 1.48.7 (20.7), 148.3 (15.6), 135.0 (16.0), and 172.9 (14.8) for shocked fish at times 0, 1, 3, and 6 h respectively, whereas these minima were only 82.5 (23.8) and 52.3 (19.8) for controls at times 0 and 6 h, respec- tively. Electroshocking did not significantly affect 70 .~, W N 60 ~~ c S0 0 ~ 40 ~ 30 ~o u ~. 20 .. 0 ~ 10 Time Attsr Shock (h) Fta. 2. Average relative concentration of corticoids in the plasma of electroshocked and unshocked trout. The lower the bar the higher the actual concentration. Numbers of fish are shown above each bar. 0 I 3 6