OBJECTIVETo evaluate the expression of nitric oxide synthase III (NOS III) mRNA in the heart, aorta, kidney and liver of spontaneously hypertensive rats (SHR).

METHODSTwo hundred and ninety-four total RNA samples were obtained from the tissues of ventricle, aortic smooth muscle, kidney and liver of SHR and normotensive rats (Wistar-Kyoto rats, WKY). RNA array was used to determine the mRNA levels of NOS III of the two groups.

RESULTSCompared with WKY, the systolic blood pressure increased significantly in SHR at 6-week-old, 8-week-old, 10-week-old and 12-week-old [(158.50 +/-7.69 vs 108.67 +/-5.89) mmHg, (174.33 +/-4.46 vs 128.50 +/-4.97) mmHg, (198.00 +/-13.45 vs 142.00 +/-3.58) mmHg, (216.67 +/-8.91 vs 141.17 +/-4.92) mmHg, P<0.01], and the ventricle/body weight ratio was significant higher at 10-week-old and 12-week-old [(4.08 +/-0.17 vs 3.59 +/-0.11, 4.05 +/-0.18 vs 3.40 +/-0.19)mg/g, P<0.01]. In the heart tissue and the kidney, the mRNA levels of NOS III were significantly increased at 6-week-old, 8-week-old, 10-week-old and 12-week-old (1.12 +/-0.18 vs 0.90 +/- 0.15, 1.46 +/- 0.34 vs 1.06 +/-0.18, 1.66 +/- 0.31 vs 1.21 +/- 0.30, 1.98 +/- 0.40 vs 1.31 +/-0.38, P <0.05) and at 4-week-old, 6-week-old, 8-week-old, 10-week-old and 12-week-old (1.10 +/- 0.21 vs 0.81 +/-0.11, 1.28 +/-0.18 vs 0.95 +/-0.13,1.31 +/-0.23 vs 0.99 +/-0.23, 1.70 +/-0.30 vs 1.08 +/-0.25, 1.83 +/-0.33 vs 1.15 +/-0.20, P<0.05 or P<0.01), respectively. There was no significant difference of the NOS III expression in the liver and no significant signals were detected in the aortic smooth muscle.

CONCLUSIONThe results provide the evidence of the increased expression of NOS III in different tissues in SHR and suggests the progressive nature of essential hypertension.