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Further Studies on Theophylline-Induced Hypocalcaemia in Sheep
Fortsatta studier över teofyllininducerad hypokalcemi hos får
Acta Veterinaria Scandinavica volume 16, pages 39–50 (1975)
Abstract
The effects of various doses of theophylline on the plasma levels of calcium, inorganic phosphorus and magnesium were studied in sheep. The dose of 0.25 mg/kg/min. during 40 min. produced a hypocalcaemia, which was abolished by thyroidectomy. At a higher dose, 1.0 mg/kg/min., thyroidectomy reduced, but did not block, the hypocalcaemic effect of theophylline. Young sheep showed a greater calcium response than did adult ewes. The decrease in plasma calcium was in no case accompanied by hypophosphataemia. Plasma magnesium decreased in all groups after 1.0 mg/kg/min. and was not influenced by thyroidectomy. Theophylline increased the urinary excretion of calcium and magnesium. It is concluded that theophylline-induced hypocalcaemia in sheep is in part a result of increased calcitonin secretion but that also other mechanisms must be involved, e. g. a direct effect of theophylline on bone.
Sammanfattning
I den föreliggande undersökningen användes får för att studera effekterna av varierande teofyllindoser på plasmakoncentrationerna av kalcium, oorganiskt fosfor och magnesium. Dosen 0,25 mg/kg/min under 40 minuter medförde en hypokalcemi, vilken ej kunde reproduceras på thyreoidektomerade djur. Vid en högre dos, 1,0 mg/kg/ min, medförde thyreoidektomin endast en reduktion av kalciumsänkningen. Hypokalcemin åtföljdes icke av hypofosfatemi. Plasmamagnesium sjönk i samtliga grupper efter dosen 1,0 mg/kg/min. Denna sänkning påverkades icke av thyreoidektomi. Teofyllin ökade urinutsöndringen av kalcium och magnesium. Teofyllininducerad hypokalcemi hos får tycks således till viss del bero på ökad kalcitoninsekretion. Även andra mekanismer måste emellertid vara inblandade, mekanismer vårs natur ännu är oklara, även om det i litteraturen finns ett visst stöd för att teofyllin skulle ha en direkt effekt på skelettet.
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Persson, J., Luthman, J. Further Studies on Theophylline-Induced Hypocalcaemia in Sheep. Acta Vet Scand 16, 39–50 (1975). https://doi.org/10.1186/BF03546694
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DOI: https://doi.org/10.1186/BF03546694