Colin L. Gibbs

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1. The average resting heat production of a muscle under zero tension is 24.8 mcal/g muscle .min at 20 degrees C. In the majority of muscles examined the resting heat production increases when the resting tension and muscle length are increased.2. The relation between actively developed tension and heat produced is similar to that existing in skeletal(More)
1. The energetic cost of work performance by mouse fast- and slow-twitch muscle was assessed by measuring the rates of thermal and mechanical energy liberation of the muscles at 21 degrees C. Thermal energy (heat) liberation was measured using a fast-responding thermopile. 2. Bundles of muscles fibres from the slow-twitch soleus and fast-twitch extensor(More)
GIBBS, C. L., AND W. R. GIBSON. Energy production of t-at soleus muscle. Am. J. Physiol. 223(4): 864-871. 1972.-A thermopile was used to record the heat production of rat soleus muscles, weighing between 16 and 96 mg, at 27 C. The muscles were subjected to isotonic and isometric tetani, 2 set in duration, and the stimulus frequency was 30 Hz. As well as(More)
1. Activation heat was estimated myothermically in right ventricular papillary muscles of rabbits using several different methods. 2. Gradual pre-shortening of muscles to a length (lmin) where no active force development took place upon stimulation led to relatively low estimates of activation heat (1.59 +/- 0.26-2.06 +/- 0.57 mJ g-1 blotted wet weight,(More)
The energy output of rabbit papillary muscle is examined and it is shown that there is more energy liberated in an afterloaded isotonic contraction than in an "equivalent" isometric contraction. This statement holds true regardless of whether equivalence is based on the proposition that tension or the time integral of tension is the best index of muscle(More)
The energy flux of rat, guinea pig, and cat papillary muscles was measured myothermically under resting, isometric, and isotonic conditions at 27 degrees C. Resting heat rate was highest in the smallest species and declined with body size. The slope of the isometric heat-stress relationship was constant across species, whereas the stress-independent heat(More)
The effect of ouabain, 0.3 /xg/tnl, on the energy output of rabbit papillary muscles has been examined by a myothermic technique. The experiments were conducted at two temperature ranges, 19.2° to 22.8°C and 29.0° to 32.2°C, and both isometric and afterloaded isotonic contractions were studied. Temperature differences alone caused pronounced physiological(More)
We endeavor to show that the metabolism of the nonbeating heart can vary over an extreme range: from values approximating those measured in the beating heart to values of only a small fraction of normal--perhaps mimicking the situation of nonflow arrest during cardiac bypass surgery. We discuss some of the technical issues that make it difficult to(More)
1. This study tested the hypothesis that moderate fatigue of skeletal muscle arises from a mismatch between energy demand and energy supply. Fatigue was defined as the decline in isometric force. Energy supply and demand were assessed from measurements of muscle heat production. 2. Experiments were performed in vitro (21 degrees C) with bundles of muscle(More)
Upon excitation of a muscle with two stimuli and variation of the interval between them up to the end of the period of full mechanical fusion, an increment of the isometric heat over that found in a single twitch is obtained. This is a good approximation to the activation heat, directly at 0 degrees C, or after certain corrections which become important at(More)