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In Wistar rats, we studied the effects of injections of a Ca 2+ channel blocker, verapamil, on realization of a food-procuring operant conditioned reflex, OCR, and general motor activity within intersignal periods in the norm and under conditions of stress-induced disorders. The OPRs and a few behavioral phenomena (immobilization, grooming, research behavior, orientational and locomotor activity, vertical stands, and intersignal limb movements in a manger) were recorded. The acute stress state was induced by intense acoustic stimulation (a loud ringing sound presented in the course of OCR realization). Inhibition of the conditioned reflex activity (immobilization of the animal within an interstimulus period) and weakening of attention to the manger resulted from stress induction. Stress-related behavioral effects evoked by intense auditory stimulation were eliminated against the background of the action of verapamil, while the OCR and motor activity were not inhibited. Verapamil suppressed reactions of fear and anxiety in a dose-dependent manner and promoted concentration of attention; these effects improved the integrative functions and abilities to adequately estimate the signals in a given situation of the OCR performance. Such effects can be based on weakening of stress-related adrenaline release and certain normalization of the state of the cardiovascular systems due to partial blocking of calcium channels.

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