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Intracarotid substance P infusion inhibits ventilation in the goat. Respir Physiol 1995 Jul;101(1):11-22 PMID: 8525117

Pubmed ID

8525117

Abstract

Substance P (SP) has been proposed as an excitatory neuromodulator of the carotid body (CB) response to hypoxia based on data from the cat and rat. The role of SP as a CB neuromodulator in the goat is unknown. Awake (n = 14) and chloralose anesthetized goats (n = 6) were used to investigate the effects of intracarotid (IC) SP infusions (1-6 micrograms.kg-1.min-1) and bolus injections (6 micrograms kg-1) to the CB intact and denervated (CBX) sides (control) on mean ventilation (VE) and mean blood pressure (MBP). In awake goats VE was decreased by infusion or bolus SP injection at a dose of 6 micrograms.kg-1 (P < 0.05) and occurred with infusions to the intact or CBX sides. MBP was elevated with SP infusion to either the CB intact or CBX sides at all SP doses. The SP antagonist CP-96,345 (0.1 mg.kg-1, IV) blocked the decrease in VE induced by SP in normoxia and significantly increased the hypoxic ventilatory response (PaO2 = 40 torr). In anesthetized goats, IC injections of SP (1 to 6 micrograms.kg-1) reduced phrenic activity and MBP before and after CBX. In only one of five goats airway pressure was increased suggesting that bronchoconstriction was not a cause for the reduced ventilatory and phrenic activity induced by SP. Immunohistochemistry provided evidence of SP in CB nerve fibers and terminals, carotid sinus nerve axons and petrosal ganglion cells, but not in type I glomus cells. Our results do not support the view that SP is an excitatory neuromodulator of CB chemotransduction in the goat.

Author List

Pizarro J, Ryan ML, Hedrick MS, Xue DH, Keith IM, Bisgard GE

Author

Melinda R. Dwinell PhD Center Associate Director, Associate Professor in the Physiology department at Medical College of Wisconsin




Scopus

2-s2.0-0029153142   13 Citations

MESH terms used to index this publication - Major topics in bold

Anesthesia
Animals
Biphenyl Compounds
Blood Gas Analysis
Blood Pressure
Carotid Body
Denervation
Depression, Chemical
Female
Goats
Immunohistochemistry
Infusions, Intra-Arterial
Male
Phrenic Nerve
Respiration
Respiratory Mechanics
Substance P
jenkins-FCD Prod-310 bff9d975ec7f2d302586822146c2801dd4449aad