Effects of acute and chronic cigarette smoking on the expression of endothelin-1 mRNA of the cardiovascular tissues in rats

Although smoking has been suggested to be involved in the development of ca rdiovascular diseases, details of the mechanism still need to be revealed. We investigated the effects of cigarette smoking on the tissue mRNA express ion of endothelin-1 (ET-1). Male Wistar rats of 4 weeks of age were exposed to smoke from six cigarettes for 30 min (acute exposure) and six cigarette s for 30 min/day, 5 days a week for 6 months (chronic exposure). Half of th e rats exposed to 6 months smoking were kept in clean-air conditions for a further 3 months to clear the effects. Tissue expression of ET-1 mRNA in th e kidney, aorta, heart and lung was determined by reverse transcriptase pol ymerase chain reaction (RT-PCR) followed by Southern blot analysis. There w as no significant difference in body and organ weight of the heart and kidn ey between the control and smoking group in either the acute or chronic exp eriment. In the acute-exposure experiment, expression of ET-1 mRNA was incr eased in the heart and lung, while that in the kidney and aorta was unchang ed. In the chronic-exposure experiment, however, there was no significant d ifference in the expression of ET-1 mRNA in all the tissues between the smo king and control groups. These results suggest that cigarette smoking could cause cardiovascular and pulmonary diseases by modulating ET-1 mRNA expres sion in the tissues.