Abstract
Previous work from this laboratory has demonstrated that the chemical activation of cell bodies in the caudal ventrolateral medulla of chloralose-anesthetized dogs decreased bronchomotor tone by withdrawing cholinergic input to airway smooth muscle. In the present study we determined the bronchomotor responses to microinjection of DL-homocysteic acid (100 mM; 25-50 nl) into the rostral ventrolateral (RVL) medulla of chloralose-anesthetized dogs. Total lung resistance was used as a functional index of bronchomotor tone. Microinjection of DL-homocysteic acid into the 20 sites located in the lateral aspect of the RVL medulla increased both total lung resistance [from 6.5 ± 0.4 to 9.1 ± 0.8 (SE) cmH2O · 1-1 · s; P < 0.05] and mean arterial pressure (from 125 ± 5 to 148 ± 8 mmHg; P < 0.05). Microinjection of this amino acid into nine sites located in the medial aspect of the RVL medulla increased mean arterial pressure (from 130 ± 6 to 153 ± 6 mmHg; P < 0.05) but had no effect on total lung resistance. We confirmed in three sites that the increase in total lung resistance evoked by microinjection of DL-homocysteic acid was accompanied by an increase in tracheal smooth muscle tension. The increase in total lung resistance evoked by DL-homocysteic acid was not affected by β-adrenergic blockade but was abolished by muscarinic blockade.
Original language | English (US) |
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Pages (from-to) | 210-216 |
Number of pages | 7 |
Journal | Journal of Applied Physiology |
Volume | 71 |
Issue number | 1 |
State | Published - 1991 |
Keywords
- brain stem
- bronchoconstriction
- cholinergic blockade
- DL-homocysteic acid
- neural control of airways
ASJC Scopus subject areas
- Endocrinology
- Physiology
- Orthopedics and Sports Medicine
- Physical Therapy, Sports Therapy and Rehabilitation