AJP - Regulatory, Integrative and Comparative Physiology, Vol 239, Issue 1 25-R30, Copyright © 1980 by American Physiological Society
Laryngeal reflex inhibition of breathing in piglets: influences of anemia and catecholamine depletion
J. C. Lee and S. E. Downing
Laryngeal reflex inhibition of breathing was studied in 31 piglets of both
sexes varying in age from 34 to 93 days. Continuing supramaximal electrical
stimulation of one superior laryngeal nerve (SLN) was associated with
spontaneous resumption of breathing within 1 min in animals more than 1 mo
of age. Respiratory rate and depth were reduced, however. In contrast with
normal piglets, electrical stimulation of the SLN in those with severe
anemia (Hct = 8.0 +/- 0.5%) caused extended apnea. An intermediate effect
was observed in animals with normal hematocrits but given reserpine (2
mg/kg) 2 days prior to study. The apnea response was potentiated in these
animals by reduction of the hematocrit from 22.8 +/- 3.4% to 8.4 +/- 1.1%
by hemodilution. In normal piglets similar degrees of hemodilution had no
discernible effects; An interrelationship between oxygen availability,
adrenergic activity, and SLN-induced respiratory depression in young
piglets is suggested by these findings.
