The effect of n_-nitro-l-arginine on the ventilatory response to
hypercapnia in the anesthetized cat.
Teppema, Luc.
AAD BERKENBOSCH AND CEES OLIEVIER LEIDEN UNIVERSITY, DEPARTMENT OF
PHYSIOLOGY, P.O. BOX 9604, 2300 RC LEIDEN, THE NETHERLANDS
APStracts 3:0430A, 1996.
The effect of intravenous administration of 40 mg x kg-1 N_-L
-Nitroarginine (L-NNA), an inhibitor of the synthesis of nitric oxide
(NO), on the ventilatory response to CO2 was studied in anesthetized
cats. The ventilatory response to CO2 was assessed during normoxia by
applying square-wave changes in end-tidal PCO2 (PETCO2 ) of about 1
kPa. Each CO2 response was separated into a fast peripheral and slow
central component characterized by a CO2 sensitivity, time constant,
time delay and an off-set (apneic threshold). L-NNA reduced the
peripheral (Sp), central CO2 sensitivity (Sc) and the apneic
threshold significantly by about 30%. However, the ratio Sp/Sc was
not changed. It is argued that the reduction in Sp and Sc, the ratio
Sp/Sc remaining constant, may be due to a potent inhibitory action of
L-NNA on the brain stem respiratory integrating centers and on the
neuromechanical link between these centers and respiratory movements.
It is concluded that NO plays an important role in the control of
breathing.
Received 6 May 1996; accepted in final form 3 September 1996.
APS Manuscript Number A431-6.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 7 October 1996