Effect of desipramine on spontaneous arterial pressure oscillations in therat

There has been no previous report on the effect of the noradrenaline uptake inhibitor desipramine on short-term variability of arterial pressure. Mean arterial pressure was recorded in 9 conscious resting rats during 4 consec utive 30-min periods: (1) under baseline conditions, (2) after desipramine administration (2 mg/kg i.v., followed by 1 mg/kg every hour), then after ( 3) cardiac autonomic blockade with methylatropine and atenolol, and (4) alp ha-adrenoceptor blockade with phentolamine. Fast Fourier transform analysis was applied to beat-to-beat data after resampling at 10 Hz of consecutive 205-s time series. Desipramine did not change the mean level and overall va riability of mean arterial pressure. However, spectral power in the mid-fre quency (0.3-0.5 Hz) band containing the Mayer waves was reduced by more tha n 80%, and power in the low-frequency (0.05-0.2 Hz) band was enhanced by ap proximately 50%, especially due to the appearance of a major oscillation ce ntred at 0.095 +/- 0.005 Hz. This slow oscillation was further enhanced aft er cardiac autonomic blockade and was abolished after ol-adrenoceptor block ade. In conclusion, desipramine profoundly alters short-term arterial press ure variability in resting rats, mainly by shifting vasomotor waves from 0. 4 to 0.1 Hz. Desipramine may prove a valuable pharmacological tool to study the dynamic aspects of arterial pressure control. (C) 1999 Elsevier Scienc e B.V. All rights reserved.