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78 J. FISH. RES. BOARD CAN., VOL. 33(1), ]976 RESPIRATORY AND CARDIAC ACTIVITY We shocked rainbow trout (168-231 g) in the laboratory for various periods to determine the effects of electroshock on respiratory and cardiac activity. Silver ECG electrodes were implanted, one just anterior and lateral to the heart and another just posterior and on the contralateral side of the heart. A buccal cannula consisting of PE 60 polyethylene tubing was inserted just lateral to the vomer. Buccal pressure as a measure of breathing movement was monitored with a Statham Laboratories pressure transducer (P 23 BB). Breathing and cardiac ac- tivities were recorded on a Grass polygraph. T'he fish were starved for 24 h before surgery and during the experiment. One control fish and two treatment fish were used in each test. The control fish was placed in a wooden box in which the flowing water supply was in parallel with that for the test fish. Test fish were placed into a wooden frame chamber that was covered with transparent netting of nylon mono- filament (Vexar©). The dimensions of the test and control chambers were such that they did not restrict breathing of the fish or movement of the paired fins but prevented swimming in any direction and turning. Two test chambers were suspended at middepth and perpendicular to the long axis of a 2009 cm x 55 cm x 44 cm flowing water trough. The water temperature was 15 C; hardness (CaCO,) was 40 mg/filer, and conductivity was 80 µmho. We covered the trough with a black polyethylene sheet to exclude light, thereby keeping the fish calm. Hooped-shaped electrodes (27 cm diam) were placed at either end of the trough, 1070 cm apart. A Coffelt battery backpack shocker delivering 350 V and 0.6 A DC was employed. The fish were allowed more than 16 h to recover from the surgical implantation of the ECG electrodes and cannulae before they were shocked. During this time we monitored breathing and heart rates to estab- lish baseline conditions. Two trout were shocked for a dur:~tion of 15 s. Breathing and cardiac activity returned to baseline conditions within 150 min. The same trout were then reshocked for I S s, monitored for 150 min, shocked for 60 s, and again monitored for 15 min. Two other test fish were shocked for 45 s. The monitors were disconnected during [he periods when the electrodes were energized. Each fish was checked by necropsy to determine possible gross effects of the electroshock. Breathing and heart rate responses were determined from the polygraphs. Buccal pressure peaks were measured over 1 min intervals at -1, 1, 2, S, lU, 20, 40, 60, 90, 12U, and I SU min to contrast the depth of breathing before and after shocking. Data are pre- sented as the average of each sampling times measure- ments. To make data comparable between fish, we considered the preshock amplitude to be 100% and expressed the postshock amplitudes as a percentage of the preshock levels. ISOENZYME PATTERNS To determine the effect of electroshocking on bio- chemical characters, we shocked 20 juvenile rainbow trout (Roaring River stock; average weight 29.3 -!- 1.39 g sE) for 40 s with 75 V and 1.1 A DC, delivered by a Coffelt battery backpack shocker. Immediately after shocking and before recovery from the paralysis the fish were removed from their 3700-liter circular tank. Blood was collected from the caudal artery into heparinized microhematocrit tubes, and the liver and a piece of white epaxial muscle were removed. Twenty control fish were collected by dipnet, given a blow to the head and sampled as above. Water condi- tions at Oregon State University's Smith Farm La- boratory where the experiment was carried out were: temperature 11 C, hardness (CaCO;,) 99 mg/liter, pH 7.3, and conductivity 241 µmho. We determined electrophoretic patterns of the fol- lowing isoenzyme systems using Ridgway's et al. (1970) buffer system: liver lactate dehydrogenase (LDH), tetrazolium oxidase (TO) and esterase (EST;), white muscle glucosephosphate isomerase (GPI), phosphoglucomutase (PCiM), alpha glycero- phosphate dehydrogenase (AGP), aspartate amino transferase (AA'1'), and general protein (GP), and plasma GP and LDH. White muscle malate dehydro- genase (MDH), malic enzyme (ME), and liver iso- citrate dehydrogenase (1DH) were separated on a buffer system described by Clayton and Tretiak (1972). All systems were stained as suggested by Shaw and Prasad (1970) with some minor modifica- tions. Gels were a 10.4°~o solution (wt/vol) of Elec- trostarch~ and buffer. All data were tested for homogeneity of variance. Those found to be homogenous were analyzed by the standard t-test. Nonhomogeneous data were analyzed by a /I'-test that allows comparison of means with unequal variances (Cochran and Cox 1957). Sig- nificance was determined at « _ .05. Results GENERAL PHYSIOLOGY Because our results did not differ with sex, data from both sexes were pooled, The fish were imma- ture and o1' similar weight and had similar go- nado-somatic indices, averaging 0.97 ~- 0.163% sE for males and 0.428 ± O.U39% sE for females. Therefore, the variation for some physiological ratios, such as androgen concentration with go- nadal development (Schreck et al. 1972b) and corticoid concentration with weight of fish (Singley and Chavin 1975), was not problematic. Fish that were shocked exhibited a significant (one-third) increase in mean plasma glucose levels by 3 h post treatment (Fig. 1). This eleva- tion was still present 6 h after shocking. Variances were homogenous. There was no significant dif- ference between mean plasma glucose levels of control fish sampled at time zero (X = 69.5 mg/ 100 ml) and 6 h later (3C = 66.0 mg/ 100 ml).