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Clinical Science (1998) 95, (137–142) (Printed in Great Britain)

Bronchial reactivity and intracellular magnesium: a possible mechanism for the bronchodilating effects of magnesium in asthma

Ligia J. DOMINGUEZ, Mario BARBAGALLO, Gabriele Di LORENZO, Agata DRAGO, Santi SCOLA*, Giuseppina MORICI and Calogero CARUSO†

Istituto di Medicina Interna e Geriatria, Universita degli Studi di Palermo, Via del Vespro 141, 90127 Palermo, Italy, *ARNAS Laboratorio Analisi Presidio Ospedaliero Civico e Benfratelli, Via Carmelo Lazzaro 2/A, 90100 Palermo, Italy, and †Servizio Tipizzazione Tissutale Istituto di Patologia generale, Corso Tuckory 211, 90134 Palermo, Italy

Abbreviations: FEV_1.0, forced expiratory volume in 1.0 s; PC, provocative concentration.

Correspondence: Dr Gabriele Di Lorenzo.

1. Increased bronchial smooth muscle contractility with consequent bronchial hyperreactivity are characteristic physiopathological events of asthma. Since magnesium intervenes in calcium transport mechanisms and intracellular phosphorylation reactions, it constitutes an important determinant of the contraction/relaxation state of bronchial smooth muscle. In the present study we investigated the relationship between bronchial reactivity, assessed by methacholine-provocation test, and magnesium concentrations both at extracellular and intracellular levels measured by spectrophotometry. Twenty-two patients with mild-to-moderate asthma and 38 non-asthmatic subjects with allergic rhinitis (24 allergic to Parietaria pollen and 14 allergic to Grass pollen) were recruited to the study. Exclusion criteria included renal failure, hepatic diseases, heart failure and arterial hypertension.

2. The salient finding of our study is that there is a strong positive correlation between bronchial reactivity and the level of intracellular magnesium (r = 0.72, P < 0.0001), both when the groups are analysed separately or together. Intracellular magnesium concentrations in the group of patients with asthma were significantly lower (1.8±0.01 mmol/l; n = 22) when compared with levels in rhinitis subjects allergic to Parietaria (1.9±0.01 mmol/l; n = 24, P < 0.05), and with levels in rhinitis subjects allergic to Grass pollen (2.0±0.03 mmol/l; n = 14, P < 0.05). Serum levels of the ion were similar in all groups.

3. We conclude that the level of intracellular magnesium may be an important determinant of bronchial hyperreactivity, as supported by the significant positive correlation between these two parameters in allergic patients with known bronchial hyperresponsiveness. This finding, in addition to reports of the bronchodilating effects of magnesium administration in patients with asthma, confirms the proposed role of this ion in the pathogenesis and treatment of asthma.

Received 11 February 1998; accepted 26 March 1998

The Biochemical Society and the Medical Research Society © 1998