Hypertension, Vol 17, 357-362, Copyright © 1991 by American Heart Association
GD Thomas, KP O'Hagan and EJ Zambraski
To determine if the neurotoxin 6-hydroxydopamine could be used to
chemically sympathectomize neonatal miniature swine, eight newborn swine
were treated with 6-hydroxydopamine beginning on the first day after birth
and continuing at regular intervals for the next 6 months. Six littermates
served as controls and received vehicle injections. A significant reduction
in the pressor response to intravenous tyramine (95%) and in the tissue
norepinephrine content of the kidneys, left ventricle, and gastrocnemius
muscle (more than 93%) provided evidence for an effective long-term
sympathectomy in the 6-hydroxydopamine- treated animals. In addition, the
blood pressure response of these young, chemically sympathectomized swine
to chronic deoxycorticosterone acetate treatment was evaluated. Mean
arterial pressure before deoxycorticosterone was similar in the
6-hydroxydopamine-treated (116 +/- 2 mm Hg) and control (125 +/- 5 mm Hg)
groups. One week after deoxycorticosterone, mean arterial pressure had
risen significantly by 20-22 mm Hg in both groups. Blood pressure continued
to increase in the control group, reaching a value of 163 +/- 6 mm Hg by
the third week after treatment. In contrast, mean arterial pressure in the
6- hydroxydopamine group did not increase further during weeks 2 and 3
after deoxycorticosterone. In conclusion, chronic treatment of neonatal
swine with 6-hydroxydopamine produced an animal model with an effective,
general, peripheral sympathectomy. The significant attenuation of the
hypertensive response in these sympathectomized animals lends further
support to the hypothesis that an intact sympathetic nervous system is
necessary for the full expression of deoxycorticosterone hypertension in
miniature swine.
ARTICLES
Chemical sympathectomy alters the development of hypertension in miniature swine
Department of Biology, Rutgers University, New Brunswick, N.J. 08903.
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