ATP as a source of interstitial adenosine in the rat heart

1999 ◽  
Vol 77 (8) ◽  
pp. 579-588 ◽  
Author(s):  
Mojca Lorbar ◽  
Richard A Fenton ◽  
James G Dobson, Jr.
Keyword(s):  
Electrical Stimulation ◽  
Interstitial Fluid ◽  
Contractile Function ◽  
Stellate Ganglion ◽  
Perfused Heart ◽  
Reserpine Treatment ◽  
Rat Hearts ◽  
Perfused Rat Hearts ◽  
Stimulation Of ◽  
Isolated Perfused Rat Hearts

The contribution of neuronal ATP to interstitial adenosine levels was investigated in isolated perfused rat hearts. Ventricular surface transudates, representing interstitial fluid, were analyzed for norepinephrine, ATP, and adenosine. Exocytotic release of norepinephrine was induced by electrical stimulation of cardiac efferents emanating from the stellate ganglion. Ganglion stimulation increased contractility, interstitial norepinephrine, ATP, and adenosine. Interstitial adenosine was 11- to 27-fold higher than interstitial ATP, suggesting that the released ATP is unlikely the only source of adenosine. In the presence of AOPCP (α,β-methyleneadenosine 5'-diphosphate), an ecto-5'-nucleotidase inhibitor, the ganglion-stimulated increase in interstitial ATP and adenosine reached levels similar to those in the absence of AOPCP, also suggesting that adenosine does not derive from extracellular ATP. The perfusate Ca2+ was raised from 1 to 4 mM to determine the importance of the enhanced contractile function on the levels of norepinephrine, ATP, and adenosine. The results were increases in contractility and interstitial norepinephrine, ATP, and adenosine, which were not suppressed with atenolol, indicating a norepinephrine-independent release of ATP and adenosine. Reserpine treatment and administration of guanethidine depleted the catecholamine stores and diminished the catecholamine release, respectively. However, neither agent altered Ca2+-induced increases in ATP and adenosine. It is concluded that the amount of neuronal-derived ATP is low and most likely does not contribute significantly to interstitial levels of adenosine. Furthermore, elevations in interstitial norepinephrine, ATP, and adenosine are associated with neuronal-independent increases in contractile function.Key words: perfused heart, stellate ganglion, co-transmission, calcium, and contractility.

Monitoring of mitochondrial membrane potential in isolated perfused rat heart

1984 ◽  
Vol 247 (4) ◽  
pp. H508-H516
Author(s):  
R. A. Kauppinen ◽  
I. E. Hassinen
Keyword(s):  
Membrane Potential ◽  
Mitochondrial Membrane Potential ◽  
Mitochondrial Membrane ◽  
Optical Methods ◽  
Perfused Heart ◽  
Rat Hearts ◽  
Carbonyl Cyanide ◽  
Perfused Rat Hearts ◽  
Beating Rate ◽  
Isolated Perfused Rat Hearts

Optical methods were tested for measuring the membrane potential changes of mitochondria in isolated perfused rat hearts. Safranin was found to be rapidly taken up by the Langendorff-perfused heart, and after loading with the dye there was practically no washout of the stain during perfusion with Krebs-Ringer bicarbonate solution. Staining with safranin induced the appearance of an intense absorption band in the reflectance spectrum of the heart, but the absorbance spectrum changes were not useful for monitoring the mitochondrial membrane potential changes because of interference by endogenous hemoproteins. The fluorescence intensity, however, responded in a manner which indicated that its changes originated from dye attached to the mitochondria. A decrease of the fluorescence was found on energizing the mitochondria by decreasing the cellular energy consumption by arrest induced by 18 mM K+ or by decreasing the beating rate of an electrically paced heart from 5 Hz to the endogenous ventricular frequency of 1.5 Hz. In hearts arrested by Ca2+ depletion, 18 mM K+ did not affect the safranin fluorescence. This was taken to indicate that under these conditions the safranin fluorescence was not sensitive to the plasma membrane potential. The uncoupler carbonyl cyanide m-chlorophenylhydrazone induced an intense enhancement of safranin fluorescence in the perfused heart, demonstrating that the probe is sensitive to mitochondrial membrane potential.(ABSTRACT TRUNCATED AT 250 WORDS)

Inhibition of nitric oxide synthesis does not affect ischemic preconditioning in isolated perfused rat hearts

1995 ◽  
Vol 268 (1) ◽  
pp. H242-H249 ◽  
Author(s):  
E. O. Weselcouch ◽  
A. J. Baird ◽  
P. Sleph ◽  
G. J. Grover
Keyword(s):  
Nitric Oxide ◽  
Ischemic Preconditioning ◽  
Coronary Flow ◽  
Constant Pressure ◽  
Contractile Function ◽  
No Synthase ◽  
Constant Flow ◽  
Rat Hearts ◽  
Perfused Rat Hearts ◽  
Isolated Perfused Rat Hearts

Endothelium-derived nitric oxide (NO) has recently been reported to be a mediator of ischemic preconditioning in dog hearts. The aim of the present study was to determine the role of NO in ischemic preconditioning in isolated perfused rat hearts. Rat hearts were perfused at either constant pressure (80 mmHg) or constant flow. After aerobic perfusion (37 degrees C) for 10 min, hearts were treated with N omega-nitro-L-arginine methyl ester (L-NAME; 30 microM), which is an inhibitor of NO synthase, or vehicle. Ten minutes later, the hearts were preconditioned (4 episodes of 5 min of global ischemia and 5 min of reperfusion) or perfused normally before a 30-min global ischemic period. All hearts were reperfused for 30 min. Coronary flow or perfusion pressure plus heart rate and contractile function were measured continuously. Hearts perfused at constant pressure and treated with 30 microM L-NAME, a concentration that effectively inhibits endogenous NO synthesis, exhibited decreased coronary flow after 10 min, and flow remained decreased throughout the experiment. Ischemic preconditioning before 30 min of global ischemia resulted in a doubling of contractile function and a reduction of lactate dehydrogenase release at the end of the 30-min reperfusion period compared with nonpreconditioned hearts. The protective effect of preconditioning was not different in L-NAME-treated hearts. In addition, inhibition of NO synthase had no effect on the severity of ischemia in nonpreconditioned hearts. Similar results were obtained in preconditioned hearts that were perfused at constant flow, indicating that the flow reductions caused by L-NAME did not influence the results.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals The effects of lactate, acetate, glucose, insulin, starvation and alloxan-diabetes on protein synthesis in perfused rat hearts

1986 ◽  
Vol 236 (2) ◽  
pp. 543-547 ◽  
Author(s):  
D M Smith ◽  
S J Fuller ◽  
P H Sugden
Keyword(s):  
Protein Synthesis ◽  
Time Course ◽  
Diabetic Rats ◽  
Perfused Heart ◽  
Translational Activity ◽  
Rat Hearts ◽  
Perfused Rat Hearts ◽  
Percentage Basis ◽  
Perfused Hearts ◽  
Stimulation Of

Compared with glucose, lactate + acetate stimulated ventricular protein synthesis in anterogradely perfused hearts from fed or 72 h-starved rats. Stimulation was greater on a percentage basis in starved rats. Atrial protein synthesis was not detectably stimulated by lactate + acetate. Insulin stimulated protein synthesis in atria and ventricles. The stimulation of protein synthesis by lactate + acetate and insulin was not additive, the percentage stimulation by insulin being less in the ventricles of lactate + acetate-perfused hearts than in glucose-perfused hearts. Perfusion of hearts from 72 h-starved or alloxan-diabetic rats with glucose + lactate + acetate + insulin did not increase protein-synthesis rates or efficiencies (protein synthesis expressed relative to total RNA) to values for fed rats, implying there is a decrease in translational activity in these hearts. In the perfused heart, inhibition of protein synthesis by starvation and its reversal by re-feeding followed a relatively prolonged time course. Synthesis was still decreasing after 3 days of starvation and did not return to normal until after 2 days of re-feeding.

Mechanism of membrane phospholipid degradation in ischemic-reperfused rat hearts

1989 ◽  
Vol 257 (1) ◽  
pp. H252-H258 ◽  
Author(s):  
H. Otani ◽  
M. R. Prasad ◽  
R. M. Jones ◽  
D. K. Das
Keyword(s):  
De Novo ◽  
Significant Loss ◽  
Membrane Phospholipid ◽  
Membrane Phospholipids ◽  
Perfused Heart ◽  
Rat Hearts ◽  
Perfused Rat Hearts ◽  
Phospholipid Degradation ◽  
Isotopic Incorporation ◽  
Stimulation Of

We investigated the mechanism of membrane phospholipid degradation during reperfusion of ischemic myocardium using isolated and perfused rat hearts. Thirty min of myocardial reperfusion after 30 min of normothermic global ischemia resulted in a significant decrease of phosphatidylcholine (PC) content associated with a small but significant increase in lysophosphatidylcholine (LPC) content. Myocardial ischemia for up to 60 min caused no significant loss of any of the major phospholipids. Isotopic incorporation of [14C]arachidonic acid (AA) as well as [3H]-glycerol into PC was significantly attenuated in the ischemic-reperfused heart compared with the normally perfused heart, suggesting that both reacylation and de novo pathways for PC synthesis were inactivated during reperfusion. In the heart prelabeled with [14C]AA, the radiolabeled PC was decreased significantly during reperfusion, associated with a small but significant increase in [14C]AA accumulation. The decreases of PC content and incorporation of [14C]AA into PC, as well as the increases of LPC content and the [14C]AA during reperfusion, were prevented by reperfusion with low Ca2+ (50 microM) buffer or by pretreatment with trifluoperazine (10 microM) or mepacrine (50 microM), but not with verapamil (1 microM). The inhibition of loss of PC was associated with significant diminution of creatine kinase release from the reperfused hearts. The present study indicates that the net loss of membrane phospholipids, especially with respect to PC during reperfusion, may result from 1) inhibition of reacylation of AA, 2) inhibition of de novo synthesis, and 3) stimulation of phospholipase activity. These results are consistent with an influx of Ca2+, although other interpretations are also possible.

Protective effects of histidine during ischemia-reperfusion in isolated perfused rat hearts

1993 ◽  
Vol 264 (5) ◽  
pp. H1370-H1381 ◽  
Author(s):  
R. C. Kukreja ◽  
K. E. Loesser ◽  
A. A. Kearns ◽  
S. A. Naseem ◽  
M. L. Hess
Keyword(s):  
Coronary Flow ◽  
Contractile Function ◽  
Ischemia Reperfusion ◽  
Protective Effects ◽  
Oxygen Scavenging ◽  
Rat Hearts ◽  
Dose Dependent Fashion ◽  
Perfused Rat Hearts ◽  
Ultrastructural Damage ◽  
Isolated Perfused Rat Hearts

We investigated the efficacy of histidine in reducing ischemia-reperfusion (I/R)-induced myocardial injury in isolated perfused rat hearts. In I/R hearts, the contractile function and coronary flow were 59 +/- 10 and 78 +/- 6% of control. Perfusion with histidine resulted in significant increase in contractility (94 +/- 4%) and coronary flow (92 +/- 4%). The incidence of arrhythmias during reperfusion was 100% (10 out of 10) in the I/R hearts with an average duration of 12.22 +/- 1.55 (SE) min. The duration of arrhythmias was shortened to 8.24 +/- 1.46, 2.15 +/- 0.9, and 2.49 +/- 1.50 min with 10, 25, and 50 mM histidine, respectively. The duration of sinus rhythm increased from 6.26 +/- 1.56 min in I/R hearts to 10.66 +/- 1.55, 14.99 +/- 1.61, and 17.18 +/- 0.95, and 11.73 +/- 0.93 min after perfusion with 10, 25, and 50 mM histidine, and superoxide dismutase (SOD)-catalase-mannitol, respectively. Electron microscopy revealed significant ultrastructural damage of myocytes in I/R hearts, which included swelling of the mitochondria and disruption of both the sarcolemma and the myofibrils. Histidine reduced the ultrastructural damage in a dose-dependent fashion. In general, the protective effect of histidine was superior than SOD-catalase-mannitol. We conclude that histidine protects myocardium against I/R damage most likely by a singlet oxygen scavenging mechanism.

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