The biological activity of the compound Iz35, representing rigid conformer of triquinol in respect to the cardiovascular system and smooth musculature, was studied. The arterial blood pressure and heart frequency were recorded in cats and rabbits as well as the tonus of smooth musculature of bronchial tree, uterus and intestines in experiments in vivo and in vitro of rats, guinea pigs and rabbits. It was established that the compound Iz35, administered in a wide range of doses of 0.1-5 mg/kg intravenously lowered systolic arterial blood pressure, but did not change chronotropic function of the heart (statistically significantly) in contrast to isoprenaline and thymolol. The compound Iz35 and trinquinol, administered intravenously in doses off 0.01-0.1 mg/kg, manifested broncholytic effect in experiments in vivo on various models of experimental bronchospasm of guinea pigs. They had still marked spasmolytic activity (1 x 10(-9)-1 x 10(-6) g/cm2 in respect to stomach-intestinal and uterine smooth musculature. The effects of Iz35 on the cardiovascular system and smooth musculature were inhibited considerably on the background of beta-adrenergic blockade (propranolol) in comparison with triquinol. The obtained data as well as our previous studies suggest to accept that these effects of the compound Iz35 are connected mainly with affecting beta-adrenergic mediator system and it manifests double agonistic/antagonistic activity in accordance with its dose characteristic.