Synergism of atenolol and nitrendipine on hemodynamic amelioration and organ protection in hypertensive rats.
OBJECTIVE
This study was designed to investigate the possible synergism of atenolol and nitrendipine on blood pressure (BP) and blood pressure variability (BPV) reductions, baroreflex sensitivity (BRS) amelioration, and organ protection in hypertensive rats.


METHODS
The dose was 20 mg/kg for atenolol, 10 mg/kg for nitrendipine and 20 + 10 mg/kg for the combination of these two drugs. In an acute study, a single dose was given via a catheter previously inserted into the stomach in spontaneously hypertensive rats (SHR). In a subacute study, SHR, deoxycorticosterone acetate (DOCA)-salt rats, and two-kidney, one-clip (2K1C) rats were used. They received the same dose by gavage daily for 10 days. BP was measured 24 h after drug administration. In chronic studies, these drugs at the aforementioned dose were mixed into rat chow. SHR were treated for 4 months. BP was then continuously recorded for 24 h. After the determination of BRS, rats were killed for organ-damage evaluation.


RESULTS
In the acute study, it was found that the combination of atenolol and nitrendipine had an obviously greater and longer BP reduction than treatment with each of these two drugs separately. In the subacute study, an effective decrease in BP 24 h after administration was found only in the rats treated with the combination. In chronic studies, it was found that the combination possessed the obvious synergism on BP and BPV reduction, BRS amelioration and organ protection in SHR. Multiple-regression analysis showed that the decrease in left ventricular hypertrophy was most significantly related to the decrease in systolic BPV and BP, the decrease in aortic hypertrophy was most significantly related to the increase in BRS and the decrease in systolic BPV, and amelioration in the renal lesion was most significantly associated with the restoration of BRS.


CONCLUSIONS
Treatment with a combination of atenolol and nitrendipine exhibited a rapid and persistent antihypertensive effect and possessed an obvious synergism on BP and BPV reduction, BRS restoration and organ protection in hypertensive rats. The decrease in BPV and the restoration of BRS may importantly contribute to organ protection in SHR with chronic treatment.
Xie
He-Hui
HH
Department of Pharmacology, Second Military Medical University, Shanghai, China.
Miao
Chao-Yu
CY
Jiang
Yuan-Ying
YY
Su
Ding-Feng
DF
D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology*; D001011:Aorta / Q000473:pathology; D001262:Atenolol / Q000494:pharmacology*; D017704:Baroreflex / Q000187:drug effects; D001794:Blood Pressure / Q000187:drug effects; D004195:Disease Models, Animal; D004357:Drug Synergism; D006973:Hypertension / Q000188:drug therapy* / Q000473:pathology; D007668:Kidney / Q000473:pathology; D008297:Male; D009568:Nitrendipine / Q000494:pharmacology*; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D017207:Rats, Sprague-Dawley
D000959:Antihypertensive Agents; D001262:Atenolol; D009568:Nitrendipine