| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Laboratory for Physiology, Free University, Amsterdam, The Netherlands.
1. In this study we determined the temperature dependence of the mean response time of cardiac mitochondrial oxygen consumption following steps in metabolic demand. Metabolic demand was altered by stepwise changes in heart rate or in left ventricular volume at 20 and 28 degrees C. 2. Ten isolated rabbit hearts were perfused with Tyrode solution at constant oxygen tension and constant arterial flow. A balloon was inserted in the left ventricle and developed pressure was measured. Coronary venous oxygen tension was measured continuously with a Clark-type oxygen electrode. 3. The mean response time of mitochondrial oxygen consumption is defined as the first statistical moment of the impulse response function. This mean response time of mitochondrial oxygen consumption, following the change in metabolic demand, is calculated from the measured mean response time for the change in coronary venous oxygen tension by subtracting the transport time resulting from diffusion and convective transport in the blood vessels. The transport time is obtained from a model for oxygen transport developed previously. Experimental data, necessary for the model calculation, were obtained from measurement of the coronary venous oxygen tension transients following stepwise changes either in arterial oxygen tension or perfusion flow. 4. The calculated mean response times of mitochondrial oxygen consumption were 26.9 +/- 3.0 s (mean +/- S.E.M.) at 20 degrees C and 14.9 +/- 1.0 s at 28 degrees C. The mean response times of mitochondrial oxygen consumption did not differ significantly for steps in heart rate and in left ventricular volume and between upward and downward steps. 5. We suggest that intracellular calcium concentration is not the sole regulator of mitochondrial oxygen consumption in the isolated rabbit heart, since steps in heart rate and in left ventricular volume showed the same time course of oxygen uptake. 6. The mean response time of mitochondrial oxygen consumption obtained in the isolated rabbit heart at 20 degrees C did not differ significantly from the mean response time of mitochondrial oxygen consumption of isolated rabbit papillary muscle. After combining our data with previously published data on empty beating hearts at 37 degrees C, a Q10, which is the factor by which the mean response time of mitochondrial oxygen consumption increases per 10 degrees C decrease in temperature, of 2.1 was calculated.
This article has been cited by other articles:
|
|
 |
|
  J. H. G. M. van Beek, M. H. van Wijhe, M. H. J. Eijgelshoven, and J. B. Hak Dynamic adaptation of cardiac oxidative phosphorylation is not mediated by simple feedback control Am J Physiol Heart Circ Physiol, October 1, 1999; 277(4): H1375 - H1384. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
B. de Groot, C. J. Zuurbier, and J. H. G. M. van Beek Dynamics of tissue oxygenation in isolated rabbit heart as measured with near-infrared spectroscopy Am J Physiol Heart Circ Physiol, May 1, 1999; 276(5): H1616 - H1624. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 P. Sipkema, J. J.M Takkenberg, P. E.M Zeeuwe, and N. Westerhof Left coronary pressure-flow relations of the beating and arrested rabbit heart at different ventricular volumes Cardiovasc Res, October 1, 1998; 40(1): 88 - 95. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 C.J. Zuurbier and J.H.G.M. van Beek Mitochondrial Response to Heart Rate Steps in Isolated Rabbit Heart Is Slowed After Myocardial Stunning Circ. Res., July 19, 1997; 81(1): 69 - 75. [Abstract] [Full Text]
|
|
|
|
|
|
C. J Zuurbier and J. H.G.M van Beek Undiminished mitochondrial function during stunning in rabbit heart at 28{degrees}C Cardiovasc Res, July 1, 1997; 35(1): 113 - 119. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
