Effects of quantitative undernourishment, ethanol and xylene on coronary microvessels of rats

The effect of alimentary deficiency, ethanol intake and exposure to xylene on the coronary microvessels and heart weight were investigated in rats. The coronary microvessels of rats, which were undernourished for 5 weeks and which were fed ad libitum were studied with the histomorphometric method of Herrmann et al [19]. In another experiment a group of rats was fed a control liquid diet while another group was fed a liquid diet containing ethanol up to 36% of the total Joule intake. One-half of both groups were placed in an exposure chamber supplied with pure air; the other two half-groups were made to inhale air containing 1000 mg xylene/m3 for 6 h daily, 5 days a week, for a period of 4 weeks. It was found that undernourishment did not cause any morphological reactions in the microvessels and did not affect the relative heart weight. Ethanol increased the contractile activity of the wall cells of coronary microvessels, and also the relative heart weight. The effect of xylene was similar to that of the ethanol. The effect of xylene in combination with ethanol was additive on the one hand (in some parameters), on the other hand there was an inhibition between the effects of the two chemicals (in the case of the number of mv. 10.5 micron less than d less than 21 micron). It is concluded that both ethanol and xylene increase the vascular tone of coronary microvessels and this alteration causes a decrease in the nutritive myocardial blood flow. Undernourishment does not play any role in the increase of vascular tone.