Different respiratory activities of mitochondria isolated from the subendocardium and subepicardium of the canine heart
- 41 Downloads
Mitochondria were prepared from the subendocardial and subepicardial layers of the canine left ventricle. The oxidation rates of palmitate, palmitoyl carnitine and pyruvate of the mitochondria obtained from the two cardiac layers were measured. The cytochrome content and the specific activities of different beta oxidation and Krebs cycle enzymes were also measured in the two mitochondrial populations. Mitochondria isolated from the ENDO layer showed significantly higher oxidation rates than mitochondria from the EPI layer for all the three substrates. No statistically significant differences in cytochrome c+c1 and a+a3 content were found in mitochondria isolated from the two regions. No significant transmural differences were found in fatty acyl CoA, L-3-hydroxy fatty acyl CoA, succinic and malic dehydrogenase specific activities, whilst isocitric dehydrogenase (NADP) specific activity was significantly higher in mitochondria isolated from the inner layer.
In conclusion, the mitochondria isolated from the inner left ventricular layer of the canine heart show a higher oxidative capacity than subepicardial mitochondria. This difference could partly be explained by the higher specific activity of isocitric dehydrogenase in this layer. These properties of subendocardial mitochondria could represent a metabolic support for the greater contractile performance of this layer.
Key wordsmyocardial mitochondria palmitic acid oxidation rate pyruvic acid oxidation rate Krebs cycle enzymes beta-oxidation enzymes
Unable to display preview. Download preview PDF.
- 3.Camici P, Ursini F, Barsacchi R, Pelosi G, Trivella MG, Marzilli M, L'Abbate A (1981) Transmural differences of mitochondrial oxidation activities in dog's heart. Circulation 64 (suppl. IV): IV-153 (Abst)Google Scholar
- 8.Hickley KM, Dunn RB, Griffs DM Jr (1975) Transmural differences in cellular constituens of the normal canine myocardium. Physiologist 18:247 (Abst)Google Scholar
- 10.L'Abbate A, Camici P, Trivella MG, Pelosi G, Taddei L, Valli G, Placidi GF (1979) Uneven myocardial glucose utilization as determined by regional14C-deoxyglucose uptake. J Nucl Med All Sci 23, 4:167–172Google Scholar
- 11.Long JW, Martin AP, Griggs DM Jr, Dunn RB, Worbeck ML (1978) Transmural mitochondrial respiration of canine left ventricular tissue. Fed Proc. 37:230 (Abst)Google Scholar
- 13.Lundsgaard-Hansen P, Meyer P, Meyer C, Riedwy M (1967) Transmural gradients of glycolytic enzyme activities in left ventricular myocardium. Arch Ges Physiol 297:89–95Google Scholar
- 14.Marzilli M, Sabbah HN, Stein PD (1979) Contractile performance of the subendocardial and subepicardial layers of the canine left ventricle. Circulation 59–60 (suppl. II):II-213 (Abst)Google Scholar
- 18.Platner WS, Griggs DM Jr, Dunn RB, McDonough KM, Abas MB (1978) Transmural mitochondrial fatty acids of canine and porcine left ventricular tissue. Fed Proc 37:781 (Abst)Google Scholar
- 19.Sottocasa GL, Knylensternia B, Ernster L, Bergstrand A (1967) Separation and some enzymatic properties of the inner and outer membranes of rat liver mitochondria. In: Methods in Enzymology, vol 10. Academic Press, New York London, 448–463Google Scholar
- 21.Winbury MM, Weiss HR, Howe RB, A Maseri, editor, Torino, Minerva Medica (1972) Inhomogeneity of oxygen tension, tissue perfusion and small vessels blood content in the left ventricle. Effect of nitrate and non-nitrate coronary dilators. In: Myocardial Blood Flow in Man. 37–55.Google Scholar
- 22.Whitty AJ, Dimino MJ, Elfont EA, Hughes GW, Repeck MW (1978) Transmural mitochondrial differences in myocardium. In: Recent Advances in Studies on Cardiac Structure and Metabolism, vol 11, Baltimore, University Park Press, 349–354Google Scholar