Aims: 

This study determined vascular function and nitric oxide production in adult borderline hypertensive rats (BHR) as compared to normotensive Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR).

Methods: 

Blood pressure (BP) and was measured by tail-cuff plethysmography. NO synthase (NOS) activity was determined by conversion of [3H]-L-arginine. Acetylcholine (ACh)-induced relaxation was investigated in the serotonine-precontracted femoral arteries using Mulvany-Halpern's myograph in isometric conditions.

Results: 

BP of WKY, BHR and SHR was 104±2, 141±5 and 192±3 mmHg, respectively (p< 0.01 among all). Relative left ventricular (LV) mass was increased significantly in both BHR and SHR vs. WKY. No genotype-related differences were observed in NOS activity in the hypothalamus. However, NOS activity was elevated significantly in the aorta of BHR (by about 81%) and SHR (by about 106%) vs. WKY and in the LV of SHR (by about 96%) vs. WKY. Maximal endotheliumdependent vasorelaxation (determined as Emax using acetylcholine test) was reduced significantly in BHR (3.96±0.12 mN/mm) and SHR (2.83±0.19 mN/mm) vs. WKY (4.80±0.15 mN/mm). Nitric oxide (NO)-dependent component of vasorelaxation was not different among genotypes. However, NO-independent component of vasorelaxation correlated negatively with BP (r = -0.66, p< 0.001) and it was reduced significantly in BHR and SHR vs. WKY.

Conclusion: 

Data showed that LV hypertrophy and NO-independent endothelial dysfunction were present already in BHR. Thus, results suggest that vascular alterations in adult borderline hypertensive rats are qualitatively similar to those observed in rats with fully developed hypertension.

Study was supported by the grants VEGA 2 /0084/10 and APVV-0523-10.