Faculty Collaboration Database

Ventilatory responses to cooling the ventrolateral medullary surface of awake and anesthetized goats. J Appl Physiol (1985) 1995 Jan;78(1):247-57

Date

01/01/1995

Pubmed ID

7713820

DOI

10.1152/jappl.1995.78.1.247

Scopus ID

2-s2.0-0028821031 (requires institutional sign-in at Scopus site)   38 Citations

Abstract

The ventrolateral medulla (VLM) has been reported to be important as a source of tonic facilitation of dorsal respiratory neurons and as a site critical for respiratory rhythmogenesis. We investigated these theories in awake and anesthetized goats (n = 13) by using chronically implanted thermodes to create reversible neuronal dysfunction at superficial VLM sites between the first hypoglossal rootlet and the pontomedullary junction (area M (rostral) and area S). During halothane anesthesia (arterial PCO2 = 57.4 +/- 4.5 Torr), bilateral cooling (thermode temperature = 20 degrees C) of 60-100% of areas M and S for 30 s produced a sustained apnea (46 +/- 4 s) that lasted beyond the period of cooling. While the animals were awake (arterial PCO2 = 36.0 +/- 1.9 Torr), cooling the identical region in the same goats resulted in a decrease (approximately 50%) in pulmonary ventilation, with a brief apnea seen only in one goat. Reductions in both tidal volume and frequency were observed. Qualitatively similar responses were obtained when cooling caudal area M-rostral area S and rostral area M, but the responses were less pronounced. Minimal effects were seen in response to cooling caudal area S. During anesthesia, breathing is critically dependent on superficial VLM neurons, whereas in the awake state these neurons are not essential for the maintenance of respiratory rhythm. Our data are consistent with these superficial VLM neuronal regions providing tonic facilitation to more dorsal respiratory neurons in both the anesthetized and awake states.

Author List

Ohtake PJ, Forster HV, Pan LG, Lowry TF, Korducki MJ, Aaron EA, Weiss EM

Author

Hubert V. Forster PhD Professor in the Physiology department at Medical College of Wisconsin

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

Anesthesia
Animals
Blood Gas Analysis
Body Temperature
Cold Temperature
Female
Goats
Male
Medulla Oblongata
Neurons
Respiratory Mechanics