Fluorometric Studies of Oxidative Metabolism in Isolated Papillary Muscle of the Rabbit

Chapman, J. D.

doi:10.1085/jgp.59.2.135

Cited by 100 publications

(38 citation statements)

References 32 publications

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“…The effects of pyruvate on the resting (NADH) fluorescence of rabbit papillary muscles was first described by Chapman [217]. Subsequently, Chapman and Gibbs [97], in myothermic studies on papillary muscles, reported that increments of 70% or more in the resting heat rate of quiescent papillary muscles were possible, and it was noted that pyruvate also had pronounced effects on mechanical output.…”

Section: Modifiers Of Basal Metabolismmentioning

confidence: 99%

Cardiac Basal Metabolism.

Gibbs

Loiselle²

2001

JJP

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The cardiac basal metabolism is the rate of energy expenditure of the quiescent myocardium. It is also called the resting metabolism or the arrested heart metabolism. It has been measured in numerous ways, and in vivo there is good evidence that it accounts for about 1/5 to 1/3 of the total energy flux. The difficulty arises, however, when the heart is stopped because the magnitude of the basal metabolism depends, as blood viscosity, on how and under what physiological condition it is measured. It is possible for the in vivo basal value to fall to less than 1/5 of its original value without cellular damage or to increase to values 5 times greater than its probable in vivo magnitude (i.e., to rise to values in excess of the energy flux of the normally beating heart) by altering the composition of the perfusion medium. We have written on this subject several times [1][2][3], but believe that developments in knowledge now make it possible for us to speculate in a more informed manner. Since several million openheart operations are performed on arrested hearts worldwide each year, it would seem imperative that we understand the cellular mechanisms that can change the magnitude of basal metabolism.A. V. Hill [4] has pointed out that in examining physiological activities, it is necessary to assume a baseline from which some quantity or rate can be measured. If the energy flux produced by the beating heart were very large compared with the energy flux of the arrested heart, baseline ambiguity would be relatively unimportant. But this is not so in regard to the heart; its basal metabolism is high. Within a species, the basal metabolism of cardiac tissue is several-fold higher than the resting metabolism of skeletal muscle and is an order of magnitude greater than the resting metabolism of amphibian skeletal muscle.Species differences are clearly evident in the magnitude of cardiac basal metabolism, and we believe that the major reason for these differences relates to the leakiness of cell membranes, such as those of the sarcolemma and sarcoplasmic reticulum and those of Japanese Journal of Physiology, 51, 399-426, 2001 Key words: whole hearts, isolated preparations, biochemical contributors, modifiers, species difference, temperature, substrate, hypoxia. Abstract: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 establish the magnitude of basal metabolism in vivo. We consider some of the likely contributors to its magnitude and point out that the biochemical reasons for a sizable fraction of the heart's basal ATP usage remain unresolved. We consider many of the physiological factors that can alter the basal metabolic rate, stressing the importance of substrate supply. We point out that the protective effect of hypothermia ...

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Section: Modifiers Of Basal Metabolismmentioning

confidence: 99%

Cardiac Basal Metabolism.

Gibbs

Loiselle²

2001

JJP

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“…The NADH/NAD + ratio may either increase [54,55] or decrease [52,53] in skeletal muscle during rest-to-work transition and is essentially constant in heart during transition to a higher work [56,44].…”

Section: Accepted M Manuscriptmentioning

confidence: 99%

Regulation of oxidative phosphorylation through parallel activation

Korzeniewski

2007

Biophysical Chemistry

119

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When the mechanical work intensity in muscle increases, the elevated ATP consumption rate must be matched by the rate of ATP production by oxidative phosphorylation in order to avoid a quick exhaustion of ATP. The traditional mechanism of the regulation of oxidative phosphorylation, namely the negative feedback involving [ADP] and [P i ] as regulatory signals, is not sufficient to account for various kinetic properties of the system in intact skeletal muscle and heart in vivo. Theoretical studies conducted using a dynamic computer model of oxidative phosphorylation developed previously strongly suggest the so-called each-step-activation (or parallel-activation) mechanism, due to which all oxidative phosphorylation complexes are directly activated by some cytosolic factor/mechanism related to muscle contraction in parallel with the activation of ATP usage and substrate dehydrogenation by calcium ions. The present polemic article reviews and discusses the growing evidence supporting this mechanism and compares it with alternative mechanisms proposed in the literature. It is concluded that only the each-step-activation mechanism is able to explain the rich set of various experimental results used as a reference for estimating the validity and applicability of particular mechanisms.

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“…Furthermore, fluorescence from respiratory chain (i.e. mitochondrial) NADH is enhanced over the fluorescence from cytoplasmic NADH to the point that fluctuations in cytoplasmic NADH contribute little to the fluorescence signal (J6bsis & Duffield, 1967;Chapman, 1972;O'Connor, 1977). In practice NADH is excited by focusing U.V.…”

Section: Introductionmentioning

confidence: 99%

Cerebral energy metabolism in diving and non‐diving birds during hypoxia and apnoeic asphyxia.

Bryan¹,

Jones²

1980

The Journal of Physiology

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SUMMARY1. Cerebral energy metabolism during apnoeic asphyxia and steady-state hypoxia was compared in ducks and chickens; ducks tolerate apnoeic asphyxia 3-8 times longer than chickens.2. Fluctuations in the reduced form of respiratory chain nicotinamide adenine dinucleotide (NADH) were monitored from the left cerebral hemisphere by a noninvasive fluorometric technique and used as an indicator of mitochondrial hypoxia. NADH fluorescence was expressed in arbitrary units (a.u.) where 100 a.u. was defined as the fluorescence change from normoxia to anoxia. Electroencephalogram (e.e.g.) and surface P02 were recorded from the right hemisphere.3. After 1 min of asphyxia NADH fluorescence increased by 37 a.u. + 3-60 S.E. of mean (n = 54) in paralysed chickens and 8 a.u. + 1 41 (n = 55) in paralysed ducks. After 2 min the fluorescence increased by only 15 a.u. + 1P95 in ducks.4. Both species showed an isoelectric e.e.g. when fluorescence increased by approximately 35 a.u., indicating that anaerobic ATP production in ducks did not maintain brain function (e.e.g.) for a greater accumulation of respiratory chain NADH.5. At a given decrease in tissue P02 ducks and chickens showed the same level of NADH increase, indicating that both species are equally dependent on tissue P02 for the maintenance of redox state.6. We conclude that biochemical adjustments which enhance anaerobic ATP production and/or prolong oxidative phosphorylation during progressive hypoxia are not responsible for increased cerebral tolerance to apnoeic asphyxia in the duck.

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Fluorometric Studies of Oxidative Metabolism in Isolated Papillary Muscle of the Rabbit

Cited by 100 publications

References 32 publications

Cardiac Basal Metabolism.

Cardiac Basal Metabolism.

Regulation of oxidative phosphorylation through parallel activation

Cerebral energy metabolism in diving and non‐diving birds during hypoxia and apnoeic asphyxia.

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