INDUCTION OF NITRIC-OXIDE SYNTHASE MESSENGER-RNA IN CORONARY RESISTANCE ARTERIES ISOLATED FROM EXERCISE-TRAINED PIGS

The purpose of this study was to develop a method by which endothelial cell nitric oxide synthase (ecNOS) mRNA expression could be measured in single coronary resistance arteries and to test the hypothesis that ecNOS gene expression is upregulated by exercise training. Yucatan mi niature swine were randomly assigned to exercise-trained (ET; n = 5) o r sedentary (Sed; n = 4) groups for 16 wk. Individual coronary resista nce arteries (50-100 mu m) were dissected, frozen in liquid nitrogen, and homogenized in a Lid buffer. mRNA was isolated from each vessel, a nd ecNOS gene expression was assessed using reverse transcriptase (RT) -polymerase chain reaction (PCR) standardized by coamplifying ecNOS wi th glyceraldehyde 3-phosphate dehydrogenase (GAPDH). The ecNOS-to-GAPD H amplicon ratio was significantly greater in coronary resistance arte ries isolated from ET pigs than in Sed controls. On the basis of these data, it is concluded that RT-PCR can be used on single coronary resi stance arteries to assess cell-specific mRNA expression and that ecNOS gene expression is upregulated by exercise training in porcine corona ry resistance arteries.