[Inducible nitric oxide synthase gene expression induced by moderate hypoxia in the rat left ventricular myocardium]

Moderate hypoxia might influence the induction of nitric oxide synthase (iNOS) messenger RNA (mRNA) expression in the rat left ventricular myocardium.

Seventy-two Sprague-Dawley rats were divided into two groups as follows: 1) those with controlled ventilation with air (n = 36), and 2) those with controlled ventilation with 10% oxygen as a hypoxic group (n = 36). Heart rate (HR) and mean arterial pressure (MAP) were measured during the study. Before, and 2, 4, 6, 8, or 10 hr after, inhalation of air or 10% oxygen (6 rats for each time), thoracotomy was performed and the left ventricular myocardium was removed. Total RNA was assayed by the reverse transcription-polymerase chain reaction (RT-PCR) with gene-specific primers for iNOS and glyceraldehyde-3-phosphate dehydrogenase.

In the air group, there were no significant differences in HR, MAP, and the level of iNOS mRNA throughout the study. In the hypoxic group, however, HR and MAP decreased significantly from 4 and 6 hr after inducing hypoxia, respectively. The level of iNOS mRNA increased significantly from 2 through 10 hr after inducing hypoxia.

This study demonstrated that in the rat left ventricular myocardium, iNOS mRNA expression increased from 2 hr after inducing hypoxia, and seemed to increase concomitantly with longer duration of hypoxia.