Food restriction lowers sympathetic support of blood pressure in aortic coarctation hypertension

The purpose of this study was to examine the effects of short-term food restriction on the development of aortic coarctation (AC)-induced hypertension. PC hypertension was induced in female Sprague-Dawley rats (251 ±6 g) by placing a suprarenal constricting ligature around the abdominal aorta using a blunt 21 gauge needle as a guide. Four days following AC, rats were assigned to an ad libitum fed (ADLIB; n=4) or food restricted (FR; n=5) group. FR rats received 60% of the food consumed by ADLIB rats. Following three weeks of food restriction, FR rats had significantly lower body weight (184 ±5 vs. 265 ± 5 g). Carotid and jugular catheters were implanted under halothane anaesthesia for measurement of pulsatile blood pressure and infusion of drugs in conscious rats. Food restriction resulted in a reduction in resting mean arterial pressure (145 ±9 vs. 177 ±14 mmHg), systolic blood pressure (163 ±11 vs. 213 ±22 rrmHg), diastolic blood pressure (127 ±9 vs. 147 ±9 mmHg), and heart rate (377 ±16 vs. 406 ±10 bpm) compared to ADLIB rats. There was also an attenuated depressor response to ganglionic blockade (hexamethoniunVatropine, i.V.) in FR animals (-51 ±6 vs. -88 ±5 mmHg). The cardiovascular responsiveness to graded doses of the alpha receptor agonist phenylephrine (in the ganglionic blocked rat) was not different between groups. The résulte indicate that 3 weeks of food restriction (60% of ADUB) significantly attenuates the rise in blood pressure following AC, and is accompanied by a decrease in sympathetic nervous system support of blood pressure. JMV is a Graduate Student Research Fellow, Amer. Heart Assoc., FL Affiliate