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Biomedical subjects

S Egginton

Publications and source records attributed to S Egginton.

At least 55 records · Page 3Linked to original sources
PubMed1997

Cold-induced angiogenesis in seasonally acclimatized rainbow trout (Oncorhynchus mykiss)

Seasonal acclimatization of rainbow trout induced an inverse relationship between environmental temperature and the capillary:fibre ratio of slow locomotory muscle, which increased from 1.73±0.09 in the summer (18 °C) to 2.50±0.15 in the winter (4 °C). However, the rate of capillary growth (angiogenesis) was exceeded by that of fibre growth at low temperatures such that the extensive fibre hypertrophy found at 4 °C led to a decrease in capillary density, NA(c,f), to 57 % of that found at 11 °C and 85 % of that at 18 °C. Cold-induced angiogenesis resulted in an expanded capillary bed of similar topology to the existing network, with capillary orientation deviating from that of muscle fibres by only 4­7 %. Capillary length density was maximal at 11 °C, JV(c,f)=2421±239 mm-2, which as previously described corresponds to the point when muscle blood flow is highest and the scope for aerobic swimming is greatest, reflecting an integrated response to optimize aerobic performance at intermediate temperatures. In contrast, ventricular NA(c,f) parallels heart rate and hence was highest at 18 °C, while there was no seasonal variation in myocyte diameter. Although a systemic response to seasonal adjustments in humoral factors may occur, the data reported here suggest that angiogenesis is probably stimulated by different mechanical factors in these two muscles.

Journal Article↗
PubMed1996

In vivo pericyte-endothelial cell interaction during angiogenesis in adult cardiac and skeletal muscle.

Pericytes (PC) exert an inhibitory effect on endothelial cell (EC) proliferation in vitro and withdrawal of PC occurs prior to EC proliferation during pathological capillary growth in vivo. Using stereological analyses of PC and capillary EC fine structure, we have studied their relationship during the early stages of physiological angiogenesis using two in vivo models. In rat skeletal muscle where capillary growth was induced by indirect electrical stimulation, there was a reduction in the relative area of contact between pericytes and the capillary abluminal surface (22% vs 30% for normal controls; P < 0.05) and pericyte surface: volume ratio (12.5 vs 14.9 microns-1 for normal controls; P < 0.05) after 3 days of stimulation, at a time prior to the appearance of new capillaries. Further withdrawal of pericyte processes was evident at the point where an actual increase in capillary numbers was observed (7 days stimulation; PC surface: volume ratio = 10.4 microns-1), although the degree of PC-EC interdigitation increased. Similar changes, but to a lesser extent, were observed in both left ventricular myocardium and papillary muscles of pigs following 4-5 weeks chronic heart rate reduction. Although PC coverage of capillaries in the heart was found to be less than that in skeletal muscle, the relative contact area between PC and capillaries also showed a reduction in paced vs sham-operated control heart (papillary: 15% vs 20%; ventricle: 12% vs 16%; P < 0.05). Interdigitation of PC and EC was absent in cardiac muscle. These data suggest that retraction of PC may play a permissive role in controlling angiogenesis in vivo in normal adult tissue.

Animals↗
PubMed1996

Effect of temperature on the resistance of individual red blood cells to flow through capillary-sized apertures.

Low temperature can be expected to increase the resistance to deformation of red blood cells, but the effect of such changes on microcirculatory perfusion are unknown. We therefore analysed resistance to flow through capillary-sized apertures for individual human red blood cells, by micropipette aspiration (approximately 3 microm aperture) and pore transit analysis (approximately 5 microm), as well as average resistance to flow of red cell suspension through multipore filters (5-microm pores). Over a range decreasing from 37 to 0 degrees C, rates of flow of single cells through the 3- and 5-microm apertures decreased monotonically by 2.5- to 3-fold. The changes were similar in magnitude to that expected for the viscosity of aqueous fluid (2.5-fold increase). Average flow resistance measured by bulk filtration also increased in line with viscosity of water, while tendency to block pores was not increased. Micropipette aspiration of small membrane tongues showed that membrane rigidity increased as temperature was lowered, but by a factor rather less than the viscosity. Cell volume also responded rapidly to change in temperature, with lower temperature being associated with swelling, although this effect was much reduced in plasma compared with saline buffer. We conclude that, although increased resistance to deformation of red cells may impair microcirculation at low temperature, there is no structural change likely to induce more dramatic occlusion of flow. Moreover, the effect is comparable in magnitude to the increase predicted for changes in plasma and blood viscosity.

Adult↗
PubMed1996

In vivo angiogenesis in adult rat skeletal muscle: early changes in capillary network architecture and ultrastructure.

The individual structural stages in capillary growth have been identified during development and under pathological circumstances in adults (wound healing, tumors), but there are no data to indicate whether these steps are similar when angiogenesis is induced in a fully differentiated microvascular bed in normal, uninjured adult skeletal muscle. In this study changes in capillary ultrastructure were correlated with capillary density and network morphology to elucidate the sequelae of angiogenesis in adult rat extensor digitorum longus (EDL) muscle whose activity was increased by stimulation at 10 Hz (8 h/day). This resulted in an increased capillary/fiber (C/F) ratio (based on staining for alkaline phosphatase) after 4 days; by 7 days C/F ratio was increased further, by approximately 50%. The ultrastructure of capillary endothelium in both the EDL and extensor hallucis proprius (EHP) was similar to control muscles after 2 days of stimulation, whereas endothelial cells in some capillaries in muscle stimulated for 4 days revealed signs of metabolic activation such as proliferation of organelles (Golgi apparatus, endoplasmic reticulum, ribosomes and mitochondria) and fewer pinocytic vesicles. Luminal surfaces were often irregular with numerous pseudopodial processes. Basement membranes were always present but amorphous regions were observed, particularly near pericyte processes. Unusually small capillary profiles, with either a slit-like lumen or with cisternae but no lumen, probably represented capillary sprouts. The interstitium contained increased collagenous and granular extracellular matrix surrounding capillaries, and numerous activated fibroblasts which were closely apposed to many capillaries. Capillary growth in EHP was also evaluated by confocal microscopy using whole mounts. The complex pattern of vessels underwent remodelling between 2 and 7 days of stimulation, resulting in more tortuous capillaries with numerous sprouts and loops. These combined observations suggest that angiogenesis may occur by a combination of sprouting, intussusceptive growth and elongation; also, that activation of endothelial cells occurs at the same time as disturbance of basement membranes during the earliest phase of growth and remodelling of the capillary bed. These changes are postulated to occur in connection with increased shear stress and/or capillary wall tension, which have been demonstrated previously.

Age Factors↗
PubMed1996

Appearance of the capillary endothelial glycocalyx in chronically stimulated rat skeletal muscles in relation to angiogenesis.

The endothelial glycocalyx layer of capillaries was stained with Ruthenium Red and examined by transmission electron microscopy in rat extensor hallucis proprius muscles after 2 or 4 days of indirect electrical stimulation via implanted electrodes. The layer appeared continuous on the luminal surface of 63% capillaries in control muscles and absent 13%. This situation was reversed in muscles stimulated for 2 or 4 days, with a continuous layer in 12 and 10% of capillaries and no glycocalyx in 44 and 58%, respectively. The greater disruption of the endothelial luminal glycocalyx in capillaries from stimulated muscles suggests that flow-related shear forces on endothelial cells could be important signals for initiation of angiogenesis in actively contracting skeletal muscle.

Animals↗
PubMed1996

Seasonal temperature acclimatisation of rainbow trout: cardiovascular and morphometric influences on maximal sustainable exercise level

Adult rainbow trout (mass 600-1500 g; length 40-44 cm) were held in the laboratory for up to 28 days at seasonally appropriate temperatures. The maximal sustainable aerobic exercise level (involving slow-twitch muscle activity alone) was determined by following muscle recruitment patterns using electromyography. The mean (&plusmn; s.e.m.) speeds recorded for maximal sustainable aerobic exercise were 0.52&plusmn;0.02, 0.81&plusmn;0.06 and 0.39&plusmn;0.02 BL s-1 (body lengths per second) for animals swimming at their acclimatisation temperatures of 4, 11 and 18 &deg;C, respectively. Thus, fish acclimatised to 11 &deg;C reached the highest maximal sustainable (purely aerobic) levels of exercise. They had similar stride lengths to the 4 &deg;C animals, but generated less thrust per stride, as indicated by increased tail-beat frequency. Acclimatisation to 4 &deg;C led to an increased mass of slow muscle and more effective tail beats (greater stride length at lower frequencies), relative to animals at higher temperatures. Fish acclimatised to 18 &deg;C had the lowest stride length and a reduced aerobic swimming capacity. Sustainable levels of aerobic exercise were reflected in unchanged values for mean heart rate and arterial blood pressure between rest and imposed, graded exercise. Radiolabelled microspheres were used to determine cardiac output (V.b) and regional blood flow distribution simultaneously in fish, both at rest and while swimming, for each acclimatisation temperature. Fish acclimatised to 11 &deg;C had the greatest scope for increasing V.b. This resulted in a significant hyperaemia in slow muscle upon exercise (10-fold increase), without an active redistribution of flow from other tissues. Maximum V.b at 18 &deg;C did not differ significantly from that at 11 &deg;C but, because resting V.b was higher, the scope was reduced and was similar to that found at 4 &deg;C. Specific blood flow to the active muscle was also reduced and this, together with decreased blood oxygen content and reduced slow muscle mass, may limit aerobic swimming performance at 18 &deg;C.

Journal Article↗
PubMed1995

Development of metabolic enzyme activity in locomotor and cardiac muscles of the migratory barnacle goose.

Preflight development of the goslings was typified by rapid increases in the mitochondrial enzymes of the semimembranosus and heart ventricular muscles resulting in near-adult values by 3 wk of age. In contrast, aerobic capacity of the pectoralis muscle initially developed slowly but showed a rapid increase between 5 and 7 wk of age, in preparation for becoming airborne. Activities of glycolytic enzymes in the pectoralis muscle showed similar patterns of development as those found for the aerobic enzymes, except for hexokinase, which was low at all ages, indicating an adaptation for catabolism of both intracellular glycogen and plasma fatty acids in preference to plasma glucose. Muscle mass specific activity of citrate synthase in the pectoralis increased by only 33% from goslings during the first few days of flight, compared with premigratory geese. Activities of anaerobic glycolytic enzymes in the ventricles were low, but values for hexokinase, which is involved in the phosphorylation of plasma glucose, developed rapidly. Values for lactate dehydrogenase were also high, reflecting the capacity of the heart to catabolize plasma lactate. Substrate flux supplied by carnitine palmitoyltransferase and oxoglutarate dehydrogenase (OGD), in the pectoralis muscles of the premigratory geese, appears to have the smallest excess capacities to meet the requirements of sustained aerobic flight. The average maximum oxygen uptake for premigratory geese during flight, as indicated by values for OGD, is calculated to be 484 ml O2/min (or 208 ml O2.min-1.kg-1).

Aging↗
PubMed1995

Do fish acclimated to low temperature improve microcirculatory perfusion by adapting red cell rheology?

We have measured the rheological properties of individual red blood cells from fishes inhabiting different thermal environments and have also investigated the effects on red cells of acute in vitro temperature changes. The membrane shear elastic modulus (rigidity) increased markedly with decreasing temperature, and the dependence was similar if temperature was varied acutely in vitro or if cells were measured at normal body temperatures. Red cells from trout and Notothenia coriiceps had almost equal membrane rigidity at comparable temperatures and showed similar temperature-sensitivity in acute experiments. Entry times of trout cells into narrow (approximately 4 microm diameter) micropipettes also increased during in vitro reduction of temperature, and this could be explained largely by the temperature-dependence expected of aqueous solutions. Perhaps surprisingly, entry times did not vary when trout living at different temperatures were tested at these temperatures. Transit times of individual cells through somewhat larger pores (5 microm) in oligopore filters again increased with decreasing temperature in vitro (partly due to increasing fluid viscosity), but such transit times did show a similar temperature-dependence for cells from trout living at different temperatures. Thus, the temperature-dependence of cellular flow resistance appears to arise from variations in membrane rigidity and in the viscosity of fluid components, along with unquantified variations in components such as microtubular structures (which we found did not influence membrane rigidity but did affect pore entry time) and the cell nucleus. Thermal acclimation did not involve adaptation to compensate for increased membrane rigidity or a large pore transit time, with, at most, minor compensation in entry times into smaller pores. We conclude that impaired cellular rheology is not a major factor influencing circulation in fish at low temperature.

Journal Article↗
PubMed1994

Iloprost reduces leukocyte adhesion in skeletal muscle venules following ischaemia in a rat model of femorodistal bypass.

UNLABELLED: Intraarterial bolus treatment with the prostacyclin analogue iloprost appears to have a prolonged beneficial effect on femorodistal bypass graft flow which extends beyond the duration of its vasodilator properties. The effect of iloprost on the microcirculation rendered ischaemic over the time course of a distal bypass operation was investigated in this study without the use of fluorescent light. METHODS: A rat model was designed to allow prolonged direct observation of leukocyte-venular endothelial adhesion in a femorodistal bypass simulation. The extensor digitorum longus (EDL) muscle of 10 rats was subjected to two 30 minute periods of ischaemia by a non-venous occluding tourniquet and to simulate some of the changes of chronic ischaemia the adverse effect of ischaemia was accentuated by indirect electrical stimulation via the lateral popliteal nerve. RESULTS: Intraarterial bolus treatment with iloprost significantly reduced the total numbers of leukocytes observed in EDL venules, and the numbers exhibiting evidence of adhesion by rolling or sticking to venule endothelium compared with saline controls at one hour post ischaemia. Ischaemia induced vasodilatation and reduced shear stress by a similar and significant amount in both groups. CONCLUSION: Two periods of ischaemia and reperfusion similar to those which occur during bypass grafting resulted in changes in the distal microcirculation consistent with reperfusion injury. Intraarterial bolus treatment with iloprost prevented these leucocyte-endothelial changes. It appears iloprost may have a role in reducing leukocyte-induced reperfusion injury in femorodistal bypass surgery.

Animals↗
PubMed1994

Effect of torbafylline on muscle blood flow, performance, and capillary supply in ischemic muscles subjected to varying levels of activity.

Torbafylline, a novel xanthine derivative, was given to rats by gavage (2 x 25 mg.kg-1.day-1, morning and evening) to study its effect upon fast muscles (tibialis anterior and extensor digitorum longus) made ischemic by unilateral ligation of the common iliac artery and subjected to two types of activity imposed by chronic electrical stimulation at 10 Hz: (i) strenuous, 6 h.day-1 as 3 x 2 h with 90- to 120-min intervals or (ii) mild, 105 min.day-1 as 7 x 10-15 min with 90- or 85-min intervals for 12-14 days. Some of the deleterious effects on ischemic muscles of strenuous activity (reduced blood flow during contractions, less resistance to fatigue) were remedied by torbafylline treatment, and values normalized. Most notably, torbafylline significantly reduced the degree of capillary endothelial cell swelling. In addition, the degree of atrophy was reduced and fatigue resistance improved in muscles contralateral to ischemic, which had been impaired with the strenuous regime. Torbafylline treatment had little further effect on ischemic muscles subjected to mild stimulation, which on its own improved functional hyperemia, resistance to fatigue, and the capillaries per fibre ratio in tibialis anterior, although it did significantly increase the capillary per fibre ratio in extensor digitorum longus. These data indicate a possible role for torbafylline as an adjunct to exercise therapy for chronic muscle ischemia.

Animals↗
PubMed1994

Effect of long-term electrical stimulation on vascular supply and fatigue in chronically ischemic muscles.

Fast skeletal muscles of Sprague-Dawley rats [tibialis anterior (TA) and extensor digitorum longus (EDL)] were subjected to ischemia by unilateral ligation of the common iliac artery. In some animals, ischemia was combined with indirect electrical stimulation at 10 Hz either for 3 x 2 h (strenuous activity) or for 7 x 10-min bouts/day (mild activity). After 2 wk, muscle blood flow and fatigue were measured during 5-min isometric supramaximal twitch contractions at 4 Hz. Terminal arteriole diameters were assessed in TA by intravital microscopy at rest and during contractions. Vascular perfusion pressure in the muscles was estimated from measurements in the carotid and saphenous arteries below the site of ligation. Capillary supply was expressed in TA and EDL as capillary-to-fiber ratio on the basis of histochemical staining for capillaries. Strenuous stimulation of ischemic muscles increased their atrophy, failed to restore blood flow, and actually worsened fatigue. In contrast, mild stimulation improved perfusion pressure, increased capillary-to-fiber ratio in the glycolytic part of TA, restored dilatation of terminal arterioles during muscle contractions, and improved blood flow and muscle fatigue so that they were no longer significantly different from control muscles. Thus, an attenuated intermittent protocol may be indicated in the treatment of muscle ischemia.

Animals↗
PubMed1994

ASSESSMENT OF MAXIMUM SUSTAINABLE SWIMMING PERFORMANCE IN RAINBOW TROUT (ONCORHYNCHUS MYKISS)

Levels of swimming activity in fishes have been divided into three categories on the basis of the time a given speed can be maintained before the onset of fatigue (Beamish, 1978): sustained (more than 200 min), prolonged (20 s to 200 min) and burst swimming (less than 20 s). The locomotory capacity of a given species reflects both its lifestyle and its body form, although definitions of performance may vary. It is generally accepted that only the aerobic ('red') muscle fibres should be active at truly sustainable swimming speeds, i.e. at speeds that can be maintained indefinitely without fatigue. However, the standard laboratory method of evaluating the maximum sustainable swimming speed (Ucrit; Brett, 1964) almost certainly entails the recruitment of at least some of the rapidly fatigable fast glycolytic ('white') fibres at sub-critical speeds and undoubtedly complicates the evaluation of maximal cardiovascular performance. It would therefore be useful to have an objective and reproducible measure of truly sustainable performance that, by definition, relies solely on aerobic muscle activity. Electromyography (EMG) has been used to examine the pattern of white muscle recruitment following thermal acclimation in striped bass, Morine saxatilis (Sisson and Sidell, 1987). We wished to incorporate this method into a study of the acclimatory responses to chronic changes in environmental temperature of the cardiovascular and locomotory systems in rainbow trout (Wilson and Egginton, 1992). The present communication presents results on the cardiovascular performance and blood chemistry, at rest and during maximal aerobic exercise, of rainbow trout acclimated to 11 &deg;C, as a validation of the methodology currently in use with fish acclimated to seasonal temperature extremes (Taylor et al. 1992). Different acclimation temperatures are known to produce compensatory changes in the relative proportions of red and white muscle mass (Sidell and Moerland, 1989). The aim of these continuing investigations is to compare the anatomical, cardiovascular and locomotory limitations to aerobic exercise over the full temperature range of a eurythermal fish species.

Journal Article↗
PubMed1993

Comparative rheology of human and trout red blood cells.

We have studied the comparative rheology of individual red blood cells from humans and rainbow trout (Oncorhynchus mykiss) at their natural body temperatures. Trout red blood cells were large ellipsoids (about 16 microns x 11.5 microns x 2.5 microns) with a mean volume of 250 fl, a surface area of approximately 350 microns 2 and an elongated nucleus of about 9 microns x 5 microns. Although much larger than human red cells (diameter 8 microns, V = 92 fl, A = 136 microns 2), both theoretical calculation and experimental aspiration into micropipettes indicated that the limiting size of a cylindrical vessel that both types of cell could enter was approximately 3 microns. Nevertheless, individual trout red cells had much longer transit times through 5 microns filter pores and were much slower to enter 3-4 microns diameter micropipettes. Interestingly, the relative deformability of the trout cells depended on the pore size and applied pressure, with entry times for trout and human cells converging as pipette diameter increased. The relatively poor overall cellular deformability of the trout cells reflected their membrane rigidity (shear elastic modulus 4-5 times higher than that of human membrane), as well as their large size and the presence of a prominent nucleus. Capillary diameters in trout muscle are similar to those in the human microcirculation (about 3 microns), while systemic driving pressures are much lower. Therefore, either red cell deformability is a less critical circulatory parameter than has previously been thought, or the apparently disadvantageous blood rheology of trout is adequate because of the lower demand for tissue perfusion.

Animals↗
PubMed1993

Fine structure of capillaries in ischaemic and non ischaemic rat striated muscle. Effect of torbafylline.

Capillary ultrastructure was studied in ischaemic and contralateral extensor digitorum longus (EDL) muscle, in the diaphragm and left ventricular papillary muscle of rats with unilateral ligation of the common iliac artery (L), in ischaemic stimulated muscles (SL), and in ischaemic stimulated muscles of animals treated with a new xanthine derivative, torbafylline (SL&T). Muscles were stimulated at 10Hz via implanted electrodes 7 times/day for 2 weeks. Torbafylline or water was given by gavage morning and evening. Nominal evaluation of capillary ultrastructure revealed endothelial swelling in 52.7 +/- 8.7% (mean +/- SEM) capillaries in ischaemic muscles, 35.2 +/- 5.6% in contralateral muscles and about 30% in the diaphragm and papillary muscle. Stimulation of ischaemic muscles increased this proportion to 62.6 +/- 6.2% (not significant vs. L), 57.8 +/- 9.5% (p < 0.05 vs. L), 62.6 +/- 6.3 (p < 0.05 vs. L) and 43.7 +/- 4.2% (p < 0.05 vs. L) in ischaemic and contralateral EDL, diaphragm and papillary muscle, respectively. Administration of torbafylline reduced the proportion of swollen capillaries to 37.8 +/- 6.1.45% (p < 0.02 vs. SL) in ischaemic muscles, and to 26.2 +/- 2.1% (p < 0.001) in papillary muscle, with a smaller effect in the contralateral EDL and the diaphragm. Stereological analysis showed that stimulation led to a marked increase in capillary size vs. contralateral muscles. A similar lumen volume density across all groups (Vv = 0.36-0.39), vs. control Vv = 0.47, reflected structural heterogeneity within the capillary population of EDL. For most components this intra- animal variation obscured drug treatment effects, the exception being Vv(nucleus) which was least in SL&T. Activity in ischaemic muscles can thus result in widespread capillary endothelial damage in muscles, and attenuation of this swelling by torbafylline may explain the beneficial effect of this drug on capillary perfusion and performance.

Animals↗
PubMed1992

Regional capillary perfusion in muscles with limited blood supply: effects of torbafylline.

Severe limitation of blood supply mainly affects the oxidative regions of skeletal muscles. In mammals, they are located medially and are thus not accessible to direct observation. We therefore investigated capillary perfusion in rat tibialis anterior, which has a predominantly glycolytic cortex and oxidative core, using timed intraarterial injection of the fluorochrome thioflavine S conjugated with serum albumin. Muscles with intact blood supply were compared with those in which the blood supply had been limited for 5 weeks by unilateral ligation of the common iliac artery. The effect of a new xanthine derivative, torbafylline (1% solution, 12.5 mg/kg, in two daily doses by gavage, 7 days/week), was also studied. The capillary/fibre ratio was estimated for perfused capillaries (those filled with fluorochrome within 7.5 s after injection; Cp) and all capillaries (those subsequently stained for alkaline phosphatase; Ct), from micrographs of cryostat sections. Regional differentiation in relative capillary perfusion was evident in all muscles samples. Cp:Ct was 0.406 +/- 0.086 (mean +/- 95% CI) in the glycolytic cortex of the contralateral normal muscle, and 0.255 +/- 0.071 in the oxidative core. Muscles with limited blood supply had a significantly lower proportion of perfused capillaries, 0.119 +/- 0.056 in glycolytic and 0.034 +/- 0.038 in oxidative regions. Torbafylline treatment nearly doubled perfusion in the glycolytic regions (Cp:Ct = 0.216 +/- 0.137) and nearly quadrupled it in oxidative (Cp:Ct = 0.121 +/- 0.151) regions of ischaemic muscles. It also improved perfusion in the contralateral muscles (Cp:Ct = 0.705 +/- 0.085 in the glycolytic cortex and 0.583 +/- 0.230 in the oxidative core).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

The effect of torbafylline on enzyme activities in fast and slow muscles with limited blood supply.

1. Activities of a glycolytic enzyme--lactate dehydrogenase, LDH, and two oxidative enzymes--citrate synthase (CS), a marker for TCA cycle entry, and 3-hydroxyacyl-CoA dehydrogenase (HAD), which indicates the capacity for beta-oxidation of endogenous lipids, were measured in fast (tibialis anterior, TA, and extensor digitorum longus, EDL) and slow (soleus, SOL) muscles of Sprague-Dawley rats with intact and limited blood supply, and following treatment with the xanthine derivative torbafylline (Hoechst, Werk Albert, Wiesbaden). 2. Limitation of blood supply by unilateral ligation of the common iliac artery increased activity of LDH in fast muscles, and activity of CS and HAD in soleus. 3. Torbafylline treatment caused an increased LDH activity in intact fast muscles and decreased it in soleus, although the relative capacity for anaerobic and aerobic metabolism (indicated by the ratio of LDH and CS activities) remained unchanged in all cases. 4. Whilst having little effect on oxidative enzyme activity of fast muscles, torbafylline decreased the activity of CS but increased activity of HAD in soleus, suggesting a greater reliance on lipid metabolism. 5. The effect of arterial ligation on enzyme activity was ameliorated by treatment with torbafylline, possibly due to its effect on the microcirculation.

3-Hydroxyacyl CoA Dehydrogenases↗