Contribution of the ryanodine-sensitive fraction to capabilities of cardiac SR

Feher, Joseph; Stephens, Marilee J.; Alderson, Barbara H.; Poland, James L.

doi:10.1016/0022-2828(88)90591-3

Cited by 14 publications

(10 citation statements)

References 37 publications

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“…Once anesthetized, respiration was supported with endotracheal intubation and mechanical ventilation with room air. Pharmacological autonomic blockade was produced by the administration of intravenous atropine (0.1 mg/ kg; maximum dose, 2 mg) and hexamethonium (20)(21)(22)(23)(24)(25) Ees is the slope of the relation and VO is its volume intercept.…”

Section: Methodsmentioning

confidence: 99%

Kinetics of restitution of left ventricular relaxation.

Prabhu

Freeman

1992

Circulation Research

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Although the kinetics of cardiac systolic force restitution have been well described, the restitution kinetics of left ventricular relaxation have not been examined. animals2'3 as well as in isolated hearts4-6 and isolated muscle preparations.7-10Weir and Yue10 have shown that the time constants of mechanical restitution and postextrasystolic potentiation are very similar and that contractile response has a linear correlation with intracellular Ca'+ concentration. Their studies with ryanodine, an inhibitor of the sarcoplasmic reticulum (SR) Ca2t release channel, have defined an essential role for the SR in the force-interval relation. These investigators concluded that the relation is a physiological expression of the availability of intracellular Ca2 , which is dependent on the SR. A phenomenological model of Ca2' flux among the SR, myoplasm, and extracellular space has been proposed to describe the kinetics of the force-interval relation.6'10Despite the large body of work performed delineating cardiac systolic restitution, very little has been done to define the pattern by which the heart's ability to relax rapidly returns after a stimulus, a phenomenon we term relaxation restitution. Relaxation, like myocardial contraction, is an energy-requiring process. Myocardial crossbridge separation and sarcomere force decay are dependent on active Ca21 uptake by the SR and resultant dissociation of Ca2' from troponin C. Although sarcolemmal Na+-Ca21 exchange participates in determining intracellular Ca2' levels, it is a low-affinity transport system and probably does not play a major role during isovolumic relaxation (see Reference 11 for review).

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Section: Methodsmentioning

confidence: 99%

Kinetics of restitution of left ventricular relaxation.

Prabhu

Freeman

1992

Circulation Research

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“…In the dog the respective distribution was 37% and 46%. The total recovery of activity, calculated as (P2 + P3 + S3)/H, was 37% and 34% for the rat in the absence and presence of ryanodine; the corresponding recovery in the dog was 70% and 50%, respectively [18]. These results demonstrate that the rat CSR decays far more during the isolation procedure and that the centrifugation of CSR activity, particularly at the first centrifugation step, was markedly different in the rat compared to the dog.…”

Section: Resultsmentioning

confidence: 89%

“…The amount of activity remaining at S3, however, was only 10% of the homogenate activity in the absence of ryanodine and 6% of the activity in its presence. In the dog, the amount at S3 was 48% in the absence of ryanodine and 27% in its presence [18]. The amount of this activity which survived in the socalled SR fraction from rat heart was negligible.…”

Section: Resultsmentioning

confidence: 98%

“…We first tried to isolate rate CSR by a slight modification of the method successfully used to isolate dog CSR [18]. The evaluation of this isolation procedure (Procedure 1, as described in Methods) is shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…The first attempt to isolate rat CSR used an adaptation of the method used to isolate canine CSR [18]. Briefly, male Sprague-Dawley rats were anesthetized with i.p.…”

Section: Methodsmentioning

confidence: 99%

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Stabilization of rat cardiac sacroplasmic reticulum Ca2+ uptake activity and isolation of vesicles with improved calcium uptake activity

Feher

Lebolt

1990

Mol Cell Biochem

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The Ca2+ uptake activity of rat cardiac sacroplasmic reticulum (CSR) in ventricular homogenates is highly unstable, and this instability probably accounts for the low specific activity of Ca2+ uptake in previously reported fractions of isolated rat CSR. The instability was observed at either 0 degrees or 37 degrees, but the Ca2+ uptake activity was relatively stable at 25 degrees. The decay of Ca2+ uptake activity at 0 degrees could not be prevented by either PMSF or leupeptin, but dithiothreitol exerted some protective effects. Sodium metabisulfite prevented decay of the Ca2+ uptake activity of homogenates kept on ice but not of homogenates kept at 37 degrees. We also found that release of the CSR from the cellular debris required homogenization in high KCl. This distinguishes rat CSR from canine CSR. Isolated CSR was produced by a combination of differential centrifugation and discontinuous sucrous gradient centrifugation. The average rate of the sustained oxalate-supported calcium uptake in the resulting CSR fraction was 0.36 mumol/min-mg in the absence of CSR calcium channel blockers and 0.67 mumol/min/mg in the presence of 10 microM ruthenium red. Thus, this preparation has the advantage of containing both the releasing and non-releasing fractions of the CSR. The Ca2(+)-ATPase rates averaged 1.07 mumol/min/mg and 0.88 mumol/min-mg in the absence and presence of ruthenium red, respectively. Although these rates are higher than previously reported rates, this CSR preparation should still be considered a 'crude' preparation. A major distinction between the rat CSR and dog CSR was the lower content of Ca2(+)-ATPase in rat CSR, as judged by SDS-PAGE. Preparations of CSR isolated by this method may be useful in evaluating alterations in CSR function.

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Sarcoplasmic Reticulum Ca Uptake, Content and Release

Bers

2001

Excitation-Contraction Coupling and Cardiac Contractile Force

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Contribution of the ryanodine-sensitive fraction to capabilities of cardiac SR

Cited by 14 publications

References 37 publications

Kinetics of restitution of left ventricular relaxation.

Kinetics of restitution of left ventricular relaxation.

Stabilization of rat cardiac sacroplasmic reticulum Ca2+ uptake activity and isolation of vesicles with improved calcium uptake activity

Sarcoplasmic Reticulum Ca Uptake, Content and Release

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