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 cardiovascular diseases, details of the mechanism still need to be revealed. We investigated the effects of cigarette smoking on the tissue mRNA expression 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 cigarettes for 30 min/day, 5 days a week for 6 months (chronic exposure). Half of the 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 the kidney, aorta, heart and lung was determined by reverse transcriptase polymerase chain reaction (RT-PCR) followed by Southern blot analysis. There was no significant difference in body and organ weight of the heart and kidney between the control and smoking group in either the acute or chronic experiment. In the acute-exposure experiment, expression of ET- 1 mRNA was increased in the heart and lung, while that in the kidney and aorta was unchanged. In the chronic-exposure experiment, however, there was no significant difference in the expression of ET-1 mRNA in all the tissues between the smoking and control groups. These results suggest that cigarette smoking could cause cardiovascular and pulmonary diseases by modulating ET-1 mRNA expression in the tissues.