Cardiovascular drugs and cell metabolism

Beta-adrenoceptor blockers represent a very important group of drugs used in the treatment of several cardiovascular diseases and hyperthyroidism. Sometimes their use is limited by the occurrence of side effects, such as fatigue in the lower extremities, general tiredness the pathogenesis of these symptoms is unclear. 

Skeletal muscle has been found to be a suitable tissue for calorimetric studies of the metabolic and thermogenetic effects of these drugs. Basal studies were first carried out to develop a microcalorimetric method that would be simple but sensitive enough for studies in vitro on small samples of muscle in physiological and pathological conditions. In order to be able to apply the method to clinical situations it was important that the quantity of material required for the measurements should be of such a magnitude that could be obtained by needle biopsy [73]. Previous studies had indicated that isolated skeletal muscle fibre bundles maintained viability in vitro which reflected fairly well the metabolic situation in vivo [74]. 

Duplicate measurements of heat production rate (P) on human obliquus internus muscle using two different calorimeters static and perfusion instrument. Source reference 75. 

A simple perfusion method was found to be the most suitable, reaching usually steady state heat production values within 1 h of the start of the calorimetric experiment [75]. No difference was found between intact whole length muscle 

Heat production rate (P) of different muscles from healthy human subjects, obtained with a perfusion calorimeter without stirring. Source reference 75. 

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