AJP - Heart and Circulatory Physiology, Vol 256, Issue 3 607-H612, Copyright © 1989 by American Physiological Society
Adrenergic control of intrarenal arteries of rabbits
M. P. Owen, M. C. Taphorn and J. G. Walmsley
Department of Biomedical Sciences, University of Illinois College of Medicine Rockford, 61107.
A comparative study of the adrenergic control of two sequential rabbit
intrarenal arteries of differing diameter [intrarenal branch artery
(IRBA)-unstretched lumen diameter (ULD) approximately 300 microns and
interlobar artery (ILA)-ULD approximately 250 microns] has been conducted.
The neurogenic contractile response of isolated segments in relation to the
maximum response to l-norepinephrine (NE) was minimal (8 Hz response
approximately 30% of maximum contraction) and similar in both types of
arteries. Phentolamine (PTA) (10(-6) M) blocked neurally evoked
contractions of the IRBAs at 2, 4, and 8 Hz and of the ILAs at 2 and 4 Hz.
(8 Hz responses were not entirely blocked in 3 out of 8 ILAs.) The
sensitivity to exogenous NE decreased with a decrease in intrarenal vessel
diameter, whereas the maximum active smooth muscle cell stress to NE was
greater than 3 X 10(5) N/m2 for each vessel. All arterial segments
constricted in response to histamine (H) and NE with equal maximal effects;
however, sensitivity to H was greater in the smaller artery (ILA). The
comparative contractile responses to nerve stimulation and exogenous NE in
sequential renal arteries contrasts to the pattern of these responses in
sequential arteries in any other rabbit regional bed previously studied
(pulmonary and ear vasculature).
