scholarly journals Lactate Utilization by an In Situ Perfused Trout Heart: Effects of Workload and Blockers of Lactate Transport

1991 ◽  
Vol 155 (1) ◽  
pp. 357-373 ◽  
Author(s):  
C. LOUISE MILLIGAN ◽  
ANTHONY P. FARRELL
Keyword(s):  
Iodoacetic Acid ◽  
Cardiac Performance ◽  
Lactate Transport ◽  
Lactate Oxidation ◽  
High Workload ◽  
Heart Preparation ◽  
Disulphonic Acid ◽  
Lactate Utilization

Lactate utilization was studied in an in situ perfused trout heart preparation that was capable of performing at levels similar to in vivo maximum cardiac performance. Hearts were perfused with modified Cortland saline containing 0.5 mmol l−1 iodoacetic acid (to block endogenous glycolysis) and varying amounts of lactate (1 or 10 mmoll−1). We confirmed previous observations that lactate utilization is limited by substrate availability. However, contrary to previous observations, exogenous fuel availability did not limit cardiac performance, even at the high workload. Furthermore, when plentiful (i.e. 10 mmol l−1), exogenous lactate was preferred over endogenous fuel and was able to supply the heart's energy requirements at both the low and high workloads. Pyruvate at 10- fold greater concentration, had no apparent effect on lactate utilization at the high workload. α-Cyano-4-hydroxycinnamate (α-CIN) (2.5 mmoll−1) proved to be an unsuitable probe of lactate transport in the trout heart as it caused a reduction in both lactate utilization and cardiac performance. However, addition of 20 μmol l−1 isobutyl carbonyl lactyl anhydride or 100 μmol l−1 4-acetamido-4′-isothiocyanostilbene-2,2′-disulphonic acid (putative lactate transport blockers) to the perfusate virtually abolished lactate oxidation at the high workload without affecting cardiac performance. These observations suggest that lactate uptake by the in situ perfused trout heart is carrier-mediated.

Metabolic state of the in situ perfused trout heart during severe hypoxia

1992 ◽  
Vol 263 (4) ◽  
pp. R798-R804 ◽  
Author(s):  
P. G. Arthur ◽  
J. E. Keen ◽  
P. W. Hochachka ◽  
A. P. Farrell
Keyword(s):  
Creatine Phosphate ◽  
Severe Hypoxia ◽  
Perfused Heart ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Cause Of Failure ◽  
Intracellular Phosphate ◽  
Heart Preparation ◽  
Power Outputs

An in situ perfused heart preparation was used to study the effects of severe hypoxia in the rainbow trout, Oncorhynchus mykiss. Hypoxic trout hearts were capable of generating similar power outputs and ATP turnovers to normoxic counterparts at subphysiological work regimes. However, lactate efflux was 35-fold higher and glycolytic rate was calculated to be > 10-fold higher in hypoxic than in normoxic hearts. The surprising ability of trout hearts to withstand severe hypoxia appears to be related to the rapid removal of lactate and associated protons from the heart. An increase in power demand to normal in vivo levels caused rapid failure in hypoxic hearts. Failure was caused by a decline in stroke volume (contractility) and was not a consequence of heart rate deterioration. Hypoxia caused marked declines in the concentration of creatine phosphate but not ATP, and we suggest that an increase in intracellular phosphate was the primary cause of failure.

scholarly journals Sexual Maturity Can Double Heart Mass and Cardiac Power Output in Male Rainbow Trout

1992 ◽  
Vol 171 (1) ◽  
pp. 139-148 ◽  
Author(s):  
CRAIG E. FRANKLIN ◽  
PETER S. DAVIE
Keyword(s):  
Rainbow Trout ◽  
Body Mass ◽  
Power Output ◽  
Cardiac Performance ◽  
Mature Male ◽  
Perfused Heart ◽  
Cardiac Power ◽  
Heart Preparation ◽  
Ovary Growth

Mature male rainbow trout have significantly higher relative ventricle masses (RVM, ventricle mass as a percentage of body mass) than do immature males or females. Hatchery-reared maturing male trout had a mean RVM of 0.139%, whereas females had an RVM of only 0.074 %. Moreover, as males matured and their testes grew from 0.07 to 3.92 % of body mass, RVM more than doubled. In female trout no such heart growth occurred; RVM remained unchanged during the period of ovary growth. Cardiac performance was assessed using an in situ perfused heart preparation. Mature male trout have larger ventricles and could generate significantly greater maximum cardiac power output per kilogram body mass than could immature males or females. This enhanced cardiac performance by the mature males was attributable to delivery of greater cardiac outputs (through larger stroke volumes) and an increased ability of the heart to work against higher output pressures. Power output per gram ventricle mass was similar in both sexes. Note: Present address: Department of Zoology, University of Queensland, Brisbane 4072, Australia.

scholarly journals The Seasonal Intrinsic Cardiac Performance of a Marine Teleost

1985 ◽  
Vol 118 (1) ◽  
pp. 173-183 ◽  
Author(s):  
MARK GRAHAM ◽  
ANTHONY FARRELL
Keyword(s):  
Heart Function ◽  
Cardiac Performance ◽  
Temperature Decrease ◽  
Marine Teleost ◽  
Inotropic Effects ◽  
Sea Raven ◽  
Input Pressure ◽  
Heart Preparation ◽  
Hemitripterus Americanus

1. An in situ heart preparation was used to evaluate cardiac performance in the sea raven, Hemitripterus americanus, under physiological inflow and outflow pressure conditions. Winter and summer fish were subjected to an acute 10°C temperature change from the seasonal ambient value. The maximum cardiac output (V·b) under each temperature condition was determined by altering inflow pressure to the heart. 2. Acute temperature increase produced positive chronotropic and inotropic effects in winter fish. Acute temperature decrease produced a negative chronotropic and inotropic effect in summer fish. 3. The inotropic and chronotropic states of the heart were different in winter and summer fish. Intrinsic heart rate was higher in summer fish at all experimental temperatures. The sensitivity of the summer fish hearts to input pressure was also greater, especially during the warm experimental temperatures. 4. It was evident from heartbeat rate measurements and power output calculations that the advent of summer and winter seasons did not promote any compensatory ability in intrinsic heart function.

In vivo mechanical behavior of canine pericardium

1986 ◽  
Vol 251 (2) ◽  
pp. H349-H356 ◽  
Author(s):  
D. Mann ◽  
W. Lew ◽  
E. Ban-Hayashi ◽  
R. Shabetai ◽  
L. Waldman ◽  
...  
Keyword(s):  
Mechanical Behavior ◽  
Longitudinal Strain ◽  
Strain Difference ◽  
Segment Length ◽  
Complex Interactions ◽  
Pericardial Pressure ◽  
Heart Preparation ◽  
The Difference

We examined the in vivo mechanical behavior of the pericardium by measuring simultaneous atrial and intrapericardial pressures and mutually orthogonal, circumferential, and longitudinally oriented pericardial segment lengths (ultrasonic gauges) in 10 open-chest dogs. Venous return was varied by a combination of caval occlusion followed by volume loading. Up to a mean left atrial pressure of 25 mmHg, the pericardium lengthened virtually exclusively in the circumferential direction (n = 9). Thus, at an intrapericardial pressure of 6.0 +/- 1.0 (+/- SD) mmHg, circumferential strain (normalized to length at pericardial pressure 0 mmHg) was 0.30 +/- 0.28, whereas longitudinal strain was 0.02 +/- 0.06 (P less than 0.05). In five of these dogs, alteration of external pericardial loading by severing the pericardial diaphragmatic attachments did not change the difference between circumferential and longitudinal strain, and in two the same directional strain difference was observed during production of cardia tamponade. In three additional dogs the square of the circumferential segment length was closely correlated with the directly measured intrapericardial volume when saline was infused into the pericardial space in an in situ, arrested heart preparation. Our results indicate that there is marked directional variability in lengthening of the pericardium when the volume of its contents is altered in vivo. This phenomenon is probably the result of complex interactions between the properties of the pericardial tissue and the influence of its internal and external loads.

AMP deaminase binding in contracting rat skeletal muscle

1992 ◽  
Vol 263 (2) ◽  
pp. C287-C293 ◽  
Author(s):  
K. W. Rundell ◽  
P. C. Tullson ◽  
R. L. Terjung
Keyword(s):  
Skeletal Muscle ◽  
Iodoacetic Acid ◽  
Amp Deaminase ◽  
Energy Demands ◽  
Slow Twitch Muscle ◽  
Fast Twitch ◽  
Resting Muscle

AMP deaminase, which hydrolyses AMP to inosine 5'-monophosphate (IMP) and NH3 at high rates during excessive energy demands in skeletal muscle, is activated when bound to myosin in vitro. We evaluated AMP deaminase binding in vivo during muscle contractions to assess whether binding 1) is inherent to deamination and found only with high rates of IMP production or simply coincident with the contractile process and 2) requires cellular acidosis. AMP deaminase activity (mumol.min-1.g-1) was measured in the supernatant (free) and 10(4)-g pellet (bound) homogenate fractions of muscle of anesthetized rats after in situ contractions to determine the percent bound. In resting muscle, nearly all (approximately 90%) AMP deaminase is free (cytosolic). During contractions when energy balance was well maintained, binding did not significantly differ from resting values. However, during intense contraction conditions that lead to increased IMP concentration, binding increased to approximately 60% (P less than 0.001) in fast-twitch and approximately 50% in slow-twitch muscle. Binding increased in an apparent first-order manner and preceded initiation of IMP formation. Further, binding rapidly declined within 1 min after cessation of intense stimulation, even though the cell remained extremely acidotic. Extensive binding during contractions was also evident without cellular acidosis (iodoacetic acid-treated muscle). Thus the in vivo AMP deaminase-myosin complex association/dissociation is not coupled to changes in cellular acidosis. Interestingly, binding remained elevated after contractions, if energy recovery was limited by ischemia. Our results are consistent with myosin binding having a role in AMP deaminase activation and subsequent IMP formation in contracting muscle.

scholarly journals Maximum cardiac performance of Antarctic fishes that lack haemoglobin and myoglobin: exploring the effect of warming on nature’s natural knockouts

2019 ◽  
Vol 7 (1) ◽  
Author(s):  
Stuart Egginton ◽  
Michael Axelsson ◽  
Elizabeth L Crockett ◽  
Kristin M O’Brien ◽  
Anthony P Farrell
Keyword(s):  
Selective Advantage ◽  
Cardiac Performance ◽  
Polar Regions ◽  
Perfused Heart ◽  
Antarctic Species ◽  
Antarctic Notothenioids ◽  
Notothenia Coriiceps ◽  
Heart Preparation

Abstract Antarctic notothenioids, some of which lack myoglobin (Mb) and/or haemoglobin (Hb), are considered extremely stenothermal, which raises conservation concerns since Polar regions are warming at unprecedented rates. Without reliable estimates of maximum cardiac output ($\dot{Q}$), it is impossible to assess their physiological scope in response to warming seas. Therefore, we compared cardiac performance of two icefish species, Chionodraco rastrospinosus (Hb−Mb+) and Chaenocephalus aceratus (Hb−Mb−), with a related notothenioid, Notothenia coriiceps (Hb+Mb+) using an in situ perfused heart preparation. The maximum $\dot{Q}$, heart rate (fH), maximum cardiac work (WC) and relative ventricular mass of N. coriiceps at 1°C were comparable to temperate-water teleosts, and acute warming to 4°C increased fH and WC, as expected. In contrast, icefish hearts accommodated a higher maximum stroke volume (VS) and maximum $\dot{Q}$ at 1°C, but their unusually large hearts had a lower fH and maximum afterload tolerance than N. coriiceps at 1°C. Furthermore, maximum VS, maximum $\dot{Q}$ and fH were all significantly higher for the Hb−Mb+ condition compared with the Hb−Mb− condition, a potential selective advantage when coping with environmental warming. Like N. coriiceps, both icefish species increased fH at 4°C. Acutely warming C. aceratus increased maximum $\dot{Q}$, while C. rastrospinosus (like N. coriiceps) held at 4°C for 1 week maintained maximum $\dot{Q}$ when tested at 4°C. These experiments involving short-term warming should be followed up with long-term acclimation studies, since the maximum cardiac performance of these three Antarctic species studied seem to be tolerant of temperatures in excess of predictions associated with global warming.

In vitro and in vivo polysaccharides assembly: ultrastructural and cytochemical study of growing plant cell wall components.

1978 ◽  
Vol 36 (2) ◽  
pp. 434-435
Author(s):  
D. Reis ◽  
B. Vian ◽  
J. C. Roland
Keyword(s):  
Cell Wall ◽  
Self Assembly ◽  
Plant Cell Wall ◽  
Higher Plants ◽  
Three Dimensional ◽  
Cytochemical Study ◽  
Wall Components

Wall morphogenesis in higher plants is a problem still open to controversy. Until now the possibility of a transmembrane control and the involvement of microtubules were mostly envisaged. Self-assembly processes have been observed in the case of walls of Chlamydomonas and bacteria. Spontaneous gelling interactions between xanthan and galactomannan from Ceratonia have been analyzed very recently. The present work provides indications that some processes of spontaneous aggregation could occur in higher plants during the formation and expansion of cell wall.Observations were performed on hypocotyl of mung bean (Phaseolus aureus) for which growth characteristics and wall composition have been previously defined.In situ, the walls of actively growing cells (primary walls) show an ordered three-dimensional organization (fig. 1). The wall is typically polylamellate with multifibrillar layers alternately transverse and longitudinal. Between these layers intermediate strata exist in which the orientation of microfibrils progressively rotates. Thus a progressive change in the morphogenetic activity occurs.

Three-Dimensional Subcellular Organization of Hepatocytes in Intact Liver: Simultaneous Visualization of Cytoskeletal and Membrane Markers by Confocal Microscopy

1996 ◽  
Vol 54 ◽  
pp. 288-289
Author(s):  
Greg V. Martin ◽  
Ann L. Hubbard
Keyword(s):  
Three Dimensional ◽  
Integral Membrane Proteins ◽  
Polarized Secretion ◽  
Microscope Images ◽  
Computer Aided ◽  
Intracellular Organelles ◽  
Cytoskeletal Elements ◽  
Simultaneous Visualization

The microtubule (MT) cytoskeleton is necessary for many of the polarized functions of hepatocytes. Among the functions dependent on the MT-based cytoskeleton are polarized secretion of proteins, delivery of endocytosed material to lysosomes, and transcytosis of integral plasma membrane (PM) proteins. Although microtubules have been shown to be crucial to the establishment and maintenance of functional and structural polarization in the hepatocyte, little is known about the architecture of the hepatocyte MT cytoskeleton in vivo, particularly with regard to its relationship to PM domains and membranous organelles. Using an in situ extraction technique that preserves both microtubules and cellular membranes, we have developed a protocol for immunofluorescent co-localization of cytoskeletal elements and integral membrane proteins within 20 µm cryosections of fixed rat liver. Computer-aided 3D reconstruction of multi-spectral confocal microscope images was used to visualize the spatial relationships among the MT cytoskeleton, PM domains and intracellular organelles.

Evaluation of Structure-Controlled Silk Fibroin Coatings for Orthopedic Infection and In-Situ Osteogenesis: In Vitro and In Vivo

2020 ◽  
Author(s):  
Wenhao Zhou ◽  
Teng Zhang ◽  
Jianglong Yan ◽  
QiYao Li ◽  
Panpan Xiong ◽  
...  
Keyword(s):  
Silk Fibroin ◽  
Orthopedic Infection
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