Effect of reserpine on cholinesterase of the rat blood and heart

Experiments were carried out on male albino rats weighing 130-160 g. Cholinesterase activity was determined by means of a Warburg apparatus by Ammon's method [7] and utilizing certain practical recommendations made by other workers [12-14]. The animals were decapitated. Cholinesterase activity was investigated in the blood plasma and in a suspension of erythrocytes prepared by Witter's method [13]. To prepare extracts from the heart tissues the organ was washed in isotonic sodium chloride solution, dried with filter paper, and the atrium and ventricles were then weighed separately and ground in a mortar with 25 mM sodium bicarbonate solution (6 ml for the atria and i0 ml for the ventricles). Extraction continued for 1 h and the extract was separated by centrifugation. The reaction mixture consisted of 1.5 ml extract and 0.5 ml substrate dissolved in 25 mM sodium bicarbonate. The substrates used were acetylcholine (AC), acetyl-fl-methylcholine (MC), benzoylcholine (BeC), and butyrylcholine (BuC). The final concentrations of the substrates for determination of the blood cholinesterase were 6.7 mM and for determination of cholinesterase in the heart 2.2 raM. The cholinesterase activity was expressed in microliters carbon dioxide liberated during incubation for 30 rain at 37~ per 0.i ml plasma or erytl~arocyte suspension and per gram fresh weight of atria or ventricles. Deductions were made for spontaneous hydrolysis of the substrateand liberation of carbon dioxide from the erythroeytes. Reserpine (Rausedil, Hungary) was injected intraperitoneally in a single dose of 7.5 mg/kg. Cholinesterase activity was determined 8 h after the injection, when the effect of reserpine is adequately reflected [5, 9].