Na+/h+ exchange in pulmonary artery smooth muscle from
spontaneously hypertensive rats and wistar kyoto rats.
Silverman, Eric S., B. Taylor Thompson, Deborah A. Quinn, T. Bernard
Kinane, Joseph V. Bonventre, Charles A. Hales.
Pulmonary/Critical Care Unit and Renal Unit*, Dept. of Medicine,
Pulmonary Unit, Dept. of Pediatrics, Massachusetts General Hospital,
Shriners Hospitals for Crippled Children and Harvard Medical School,
Boston, MA 02114
APStracts 2:0109L, 1995.
Na+/H+ exchanger regulation of intracellular pH (pHi) may play a key
permissive role in the mitogen induced vascular smooth muscle cell
growth that occurs in systemic and pulmonary vascular remodeling.
Spontaneously hypertensive rats (SHR) have increased Na+/H+ exchange
in systemic vessels as well as greater systemic vascular remodeling
compared with normotensive Wistar Kyoto rats (WKY). In contrast to
WKY, SHR demonstrate only mild pulmonary hypertension and no
increased remodeling to hypoxia compared with WKY. We therefore
wondered if Na+/H+ exchange in pulmonary artery smooth muscle (PASM)
of SHR might not be elevated compared with WKY. Baseline pHi, Vmax,
pK0.5 and Hill coefficient were compared in 12-14 wk old SHR and WKY
PASM and aortic smooth muscle (AoSM) segments by ratio fluorescence
spectroscopy. The Vmax, pK0.5 and Hill coefficient were significantly
increased in SHR AoSM segments compared with WKY AoSM segments (53%,
0.55%, 53%, respectively) (P<0.05). Unlike the AoSM segments
there were no differences in these values between SHR and WKY PASM
segments. We conclude that in the SHR the Na+/H+ exchanger activity
in pulmonary artery smooth muscle is the same as in the WKY, which is
in contrast to systemic arteries where Na+/H+ exchange is greater in
the SHR.
Received 24 October 1994; accepted in final form 14 June 1995.
APS Manuscript Number L307-4.
Article publication pending Am. J. Physiol. (Lung Cell. Mol.
Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 11 July 1995.