1. The aim of these experiments was to determine if the vasorelaxation of the rat isolated aorta induced by sufentanil or alfentanil is mediated by the endothelium, and, if not, by a-adrenoceptor blockade, or a direct effect on the smooth muscle.2. Both sufentanil (from 10-7 mol/ L to 10-4 mol/ L) and alfentanil (from 10-7 mol/ L to 3 x 10-4 mol/ L) relaxed rings, where endothelium was intact and precontracted with 40 mmol/ L KCl, in a concentration-related manner. Similarly, sufentanil and alfentanil relaxed rings, in the presence or absence of endothelium, which had been precontracted with phenylephrine.3. Naloxone (10-4 mol/L) had no significant effect on the relaxation induced by either sufentanil or alfentanil. 4.In a similar manner as phentolamine, pretreatment with sufentanil protected a-adrenoceptors from blockade by phenoxybenzamine (PBZ) in both endothelium intact and denuded rings, but the estimated potency of sufentanil was approximately 100-fold less than that of phentolamine in aadrenoceptor protection. Treatment with alfentanil did not produce any receptor protection.5. We concluded that, in the rat aorta, vascular relaxation induced by sufentanil is mediated by both a-adrenoceptor blockade and a direct effect on smooth muscle, whilst the relaxant effect of alfentanil is caused by direct effects alone. We also concluded that the endothelium has little role in relaxation produced by either drug.

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Young men of call-up age with neurocirculatory were asthenia were examined for autonomic regulation of cardiac activity and vasodilatory reserve of the arteries. The functional state of the autonomic nervous system (ANS) was studied with the aid of rythmography with analyse of heart rate variability. The following parameters were studied: vegetative regulation type, responsiveness of departments of ANS and autonomic provision of cardiac activity. The type of vegetative regulation was determined by the mean value of RR interval and indication of the heart rate variability (∆RR). Reactivity of parasympathetic and sympathetic divisions of the ANS and autonomic support of cardiac activity were investigated using breathing test. To ensure vegetative dysadaptation cardiac activity includes reaction with low vegetative coverage of both divisions of the ANS and paradoxical reaction in which there is a decrease in ∆RRmax (instead of increase) and an increase in ∆RRmin instead of decrease. These reactions indicate autonomic dysfunction. Vasodilatory reserve of the arteries was investigated using ultrasonography of the brachial artery with compressive sample and determination of endothelium-dependent vasodilation. It was found that in boys with neurocirculatory asthenia vagotonic and sympathetic types of vegetative regulation are often determined by disadaptative vegetative provision of cardiac activity, which is accompanied by endothelial dysfunction with reduced vasodilator reserve of the arteries.

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