Hypomagnesemia resulting from adrenaline infusion in ewes: its relation to lipolysis

Intravenous infusion of adrenaline (40 microgram Kg-1 h-1 for 5 hrs) causes hypomagnesemia in ewes. Hypomagnesemia is increased by phentolamine and inhibited by propranolol. Thyroidectomy, with thyroxine supplementation, does not inhibit the hypomagnesemia caused by adrenaline and phentolamine. Sodium nicotinate (15 mg Kg-1 h-1 for 5 hrs) inhibits the increase in non-esterified fatty acids and hypomagnesemia resulting from infusion of adrenaline and phentolamine. Sodium nicotinate inhibits the increase in non-esterified fatty acids and hypomagnesemia resulting from theophylline infusion (20 mg Kg-1 h-1 for 90 min). It is concluded that an increase in the level of intra-cellular cyclic AMP due to beta adrenergic stimulation by adrenaline or to inhibition of phosphodiesterases by theophylline, results in hypomagnesemia which seems to be correlated with stimulation of lipolysis.