Effects of telmisartan on blood pressure and kidney in Wistar rats long-term intaking high-salt diet

Objective To investigate the effect of long-term intaking high-salt diet on blood pressure and kidney function in Wistar rats with or without telmisartan. Methods Forty-nine male Wistar rats were randomly divided into three groups: control group (given 0.5% NaCl, n=13), High-salt group (given 8% NaCl, n=24), and intervention group (given 8% NaCl+telmisartan, n=12). All groups had free access to water. The experiment lasted for 24 weeks. Tail systolic blood pressure was monitored by tail-cuff artery pressure-measuring instrument. The 24 h urine was collected by metabolism cage to measure the concentration of Na++, K++, microalbumin, total protein, and creatinine. At the 24th week, both kidneys were obtained to calculate the renal hypertrophy index (kidney mass/body mass). The kidney morphological changes were observed by Hematoxylin and Eosin(HE) staining and Masson staining. Results Compared to control group,blood pressure of some rats in High-salt group was continuously increased,while blood pressure of the others in this group only increased during the 8th to 10th week of the experiment. Thus the rats in High-salt group rats were further divided into High-salt hypertension group (HH group, n=12) and High-salt normal blood pressure group (HN group, n=12). In High-salt group, the renal hypertrophy index, 24 h urinal microalbumin, totel protein, sodium excretion and the ratio of Na++/K++ were increased (P0.01), while the creatinine clearance rate(Ccr) was decreased (P0.01) with tubular atrophy and necrosis, luminal expansion, and renal interstitial fibrosis. The renal damages in HN group were lighter than those in HH group. Compared to HH group, the tail systolic blood pressure, content of microalbumin and totel protein was decreased (P0.01) in intervention group,and renal damages were ameliorated. But the renal hypertrophy index, Ccr, 24 h sodium excretion, and the ratio of Na++/K++ didn't have statistically significant change (P0.05). Conclusions Long-term high-salt diet may induce persistence or transient increase in blood pressure in Wistar rats,independent of renal damages. Telmisartan has antihypertensive effects and protective effects on kidney.