Premium
Spasmolytic effect of magnesium sulfate on serotonin‐induced pulmonary hypertension and bronchoconstriction in dogs
Author(s) -
Yoshioka H.,
Hirota K.,
Sato T.,
Hashimoto Y.,
Ishihara H.,
Matsuki A.
Publication year - 2001
Publication title -
acta anaesthesiologica scandinavica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.738
H-Index - 107
eISSN - 1399-6576
pISSN - 0001-5172
DOI - 10.1034/j.1399-6576.2001.045004435.x
Subject(s) - bronchoconstriction , medicine , pulmonary hypertension , vascular resistance , anesthesia , serotonin , vasodilation , endocrinology , asthma , blood pressure , receptor
Background: Magnesium (Mg 2+ ) has relaxant effects on histamine‐induced bronchoconstriction. In addition, Mg 2+ has been reported to reduce vascular smooth muscle tone and be clinically useful for treatment of persistent pulmonary hypertension of the newborn. In this study, we evaluated the relaxant effect of Mg 2+ on serotonin (5HT)‐induced bronchoconstriction and pulmonary hypertension. Methods: Seven mongrel dogs were anesthetized with pentobarbital (30 mg · kg −1 +2 mg · kg −1 · h −1 ) and paralyzed by pancuronium (0.2 mg · kg −1 · h −1 ). Bronchoconstriction and pulmonary hypertension were elicited with 5HT (10 μg · kg −1 +1 mg · kg −1 · h −1 ). Airway caliber was evaluated by changes in bronchial cross‐sectional area (BCA) of the 3rd bronchial bifurcation measured by a fiberoptic bronchoscope method as previously reported. Pulmonary hypertension was assessed by changes in pulmonary vascular resistance (PVR). The BCA and PVR were expressed as per cent of the basal level. Thirty minutes after start of 5HT infusion, magnesium sulfate (MgSO 4 ): 0 (saline), 1, 10, 100 and 1000 μmol · kg −1 was given iv. Arterial blood was also collected to measure plasma level of Mg 2+ and catecholamines. Results: 5HT increased %PVR to 163±25% and decreased % BCA by 39.2±4.5%. Plasma level of Mg 2+ following MgSO 4 1000 μmol · kg −1 iv exceeded its toxic level. The ED 50 s of MgSO 4 (dose producing 50% relaxation of maximal constriction) was 47.8 μmol · kg −1 and 1.09 mmol · kg −1 for pulmonary hypertension and bronchoconstriction, respectively. The ratio of %PVR to %SVR was about 1.0 after MgSO 4 0–100 μmol · kg −1 iv, although the ratio significantly increased after 1000 μmol · kg −1 iv. Conclusion: In dogs, 5HT‐induced pulmonary hypertension but not bronchoconstriction was significantly reduced by an iv bolus of MgSO 4 , resulting in a plasma concentration within the assumed therapeutic level.