Altered Na, K-ATPase mRNA Expression in Spontaneously Hypertensive Rats.

Abstract

We investigated the expression of Na, K-ATPase α and β isoform mRNAs in spontaneously hypertensive rat (SHR) hearts, aortae and kidneys, compared with findings in normotensive Wistar-Kyoto rat (WKY), to obtain insight into the role of these isoforms in the development of hypertension in SHR. We used 4-, 8-, and 16-week-old SHR and WKY. Systolic blood pressure was recorded by tail sphygmomanometry. The expression of Na, K-ATPase α and β isoform mRNAs was analyzed by Northern blot hybridization, using isoform specific cDNA probes. In the ventricles, pre-hypertensive 4-week-old SHR showed a significant 3 to 4-fold increase in the α1 and α2 isoform mRNA accumulation compared with age-matched WKY. The α3 isoform mRNA expression was detected only in 4-week-old SHR hearts. The pattern of β1 mRNA expression resembled that of α1 or α2 mRNAs, and a significant 7-fold increase was observed in 4-week-old SHR compared with age-matched WKY. In the aortae, the α1 and α2 isoform mRNAs were expressed, and 4-week-old SHR exhibited a significant 5-fold increase in the α1 and α2 isoform mRNA levels compared with age-matched WKY. In the kidneys, only the α1 isoform mRNA was expressed, and that of SHR showed a significant 2-fold increase compared with age-matched WKY. We conclude that the expression of Na, K-ATPase α and β isoform mRNAs is significantly increased in the hearts, aortae and kidneys of SHR before the onset of hypertension. These findings suggest that, in this model, the altered expression of Na, K-ATPase gene is an early, if not a primary, event in the development of hypertension. (Hypertension Res 1993; 16: 269-274)