Effects of hypertension and sympathetic denervation on cerebral blood flow in newborn pigs.
To investigate the potential role of sympathetic nerves in preventing pronounced increases in cerebral blood flow, we evaluated the effects of abrupt hypertension on the cerebral circulation of newborn pigs with intact cerebral sympathetic innervation and after cerebral sympathetic denervation. Epinephrine infusion was used to induce abrupt increases in mean (+/- SEM) arterial pressure (innervated pigs, 62 +/- 3 mm of Hg to 115 +/- 3 mm of Hg; denervated pigs, 71 +/- 4 mm of Hg to 132 +/- 4 mm of Hg) that remained increased for the 3 minutes of the study. Abrupt hypertension increased blood flow to all brain regions. In denervated pigs, the increased flow to the cerebrum was prolonged, compared with that in pigs with intact sympathetic innervation. Differences between pigs of the innervated and denervated groups were not apparent, with respect to blood flow to any other region (caudate region, brain stem, cerebellum). In newborn pigs, sympathetic nerves may attenuate hypertension-induced increases in blood flow to the cerebrum, but do not appear to affect flow to the rest of the brain.
Fletcher
A M
AM
Department of Physiology and Biophysics, University of Tennessee, Memphis 38163.
Leffler
C W
CW
Busija
D W
DW
D000818:Animals; D000831:Animals, Newborn / Q000502:physiology; D001794:Blood Pressure; D002560:Cerebrovascular Circulation; D004837:Epinephrine / Q000494:pharmacology; D005260:Female; D006973:Hypertension / Q000139:chemically induced / Q000503:physiopathology*; D008297:Male; D009132:Muscles / Q000098:blood supply; D012039:Regional Blood Flow; D013552:Swine; D013562:Sympathectomy; D013564:Sympathetic Nervous System / Q000503:physiopathology*; D014655:Vascular Resistance
D004837:Epinephrine