Objective: To investigate the relationship between hypertensive microalbuminuria and vascular endothelial and glomerular impairment.
Methods: The animals were divided into the normotensive group (WKY Rat), hypertensive treated group (SHR with losartan) and untreated group(SHR). The blood pressure, level of microalbuminuria, and renal function were measured. In addition, endothelium of the mesenteric artery and glomerular mesangial cells were observed with the transmission electronic microscope in three and eight-month-old rats respectively.
Results: Significantly increased microalbuminuria was shown in SHR, which was correlated with the blood pressure and vascular endothelial volume density. Early impairment of vascular endothelium and the glomerular basement membrane was demonstrated in three-month-old SHR. However, there was no significant difference in glomerular mesangial cells and renal function between SHR and WKY rats. In the eight-month-old untreated group, the volume density of glomerular mesangial cells increased significantly, which indicated a further impairment of hypertension. The level of microalbuminuria was not correlated with the blood pressure. Compared with the untreated group, the hypertensive treated group showed a decreased volume density of vascular endothelium and glomerular mesangial cells, which was accompanied with a reduction of microalbuminuria.
Conclusion: The mechanism which causes microalbuminuria in hypertension may vary with the severity of the hypertensive condition. At the early stage, the haemodynamics mechanism seems to be the most plausible cause of microalbuminuria, whereas at the severe stage, glomerular damage and vascular remodeling are likely to play the key role. Losartan can inhibit those deteriorations besides blood pressure lowering.