Our long term objective is to understand the maintenance of upper airway patency in health and disease. the proposed studies are designed to provide better insight into mechanisms that are poorly understood at present. Special emphasis is given to neuroregulation of upper airway muscles Stimulation of laryngeal afferent is known to alter the activity of various upper airway muscles. Anesthetized, spontaneously breathing dogs and rabbits will be used in the animal studies. Action potentials from single fibers of the superior laryngeal nerve will be monitored from its peripheral cut end. Electromyograms of posterior cricoarytenoid, genioglossus and al ae nasi muscles will be recorded with bipolar wire electrodes. Behavior of laryngeal mechanoreceptors and the response of upper airway muscles during upper airway occlusion will be documented before and after paralysis of intrinsic laryngeal muscles (by cold block of recurrent laryngeal nerves). The role of volume-related feedback from the lungs on the response to upper airway pressure will be tested by blocking the activity of slowly adapting receptors with SO2 in anesthestized rabbits. The effects of cooling of the laryngeal mucosa on the mechanoreceptor response to pressure changes will be evaluated, and single fiber action potential recorded during upper airway occlusion. In separate experiments the effect on tracheal smooth muscle activity will also be studied by monitoring smooth muscle tone in the extra-thoracic trachea. The hypothesis that laryngeal cooling is responsible for the respiratory inhibition observed in newborn animals during airflow through the upper airway will be tested by comparing the responses at different laryngeal temperatures at constant flow rate. Finally, in human studies, we plan to identify the factors responsible for the alteration of breathing pattern during feeding of expressed milk and formula. In addition, the rate of milk flow will be altered using high and low flow rate nipples. The proposed studies are anticipated to provide valuable insights into airway maintenance and regulation of breathing in health and disease, especially in sleep apnea and cold-induced bronchospasm.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL032921-04
Application #
3344481
Study Section
Respiratory and Applied Physiology Study Section (RAP)
Project Start
1984-08-01
Project End
1990-06-30
Budget Start
1988-07-01
Budget End
1989-06-30
Support Year
4
Fiscal Year
1988
Total Cost
Indirect Cost
Name
University of Texas Medical Br Galveston
Department
Type
Schools of Medicine
DUNS #
041367053
City
Galveston
State
TX
Country
United States
Zip Code
77555
Ghosh, T K; Van Scott, M R; Mathew, O P (1996) Activation of water-responsive laryngeal afferents: role of epithelial ion transport. Respir Physiol 105:163-9
Naida, A M; Ghosh, T K; Mathew, O P (1996) Airway protective reflexes elicited by laryngeal ammonia: role of C-fiber afferents. Respir Physiol 103:11-7
Ghosh, T K; Van Scott, M R; Mathew, O P (1995) Epithelial modulation of afferent nerve endings: differential effects of amiloride on afferent subtypes. J Appl Physiol 78:2235-40
Ghosh, T K; Mathew, O P (1994) Influence of intralaryngeal CO2 on the response of laryngeal afferents to upper airway negative pressure. J Appl Physiol 76:2720-5
Zhang, S; Mathew, O P (1992) Decrease in lung volume-related feedback enhances laryngeal reflexes to negative pressure. J Appl Physiol 73:832-6
Zhang, S; Mathew, O P (1992) Response of laryngeal mechanoreceptors to high-frequency pressure oscillation. J Appl Physiol 73:219-23
Mathew, O P; Belan, M; Thoppil, C K (1992) Sucking patterns of neonates during bottle feeding: comparison of different nipple units. Am J Perinatol 9:265-9
Sant'Ambrogio, F B; Tsubone, H; Mathew, O P et al. (1991) Afferent activity in the external branch of the superior laryngeal and recurrent laryngeal nerves. Ann Otol Rhinol Laryngol 100:944-50
Sant'Ambrogio, G; Anderson, J W; Sant'Ambrogio, F B et al. (1991) Response of laryngeal receptors to water solutions of different osmolality and ionic composition. Respir Med 85 Suppl A:57-60
Thoppil, C K; Belan, M A; Cowen, C P et al. (1991) Behavioral arousal in newborn infants and its association with termination of apnea. J Appl Physiol 70:2479-84

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