Kwalitatiewe en kwantitatiewe verskille tussen die sarkoplasmiese retikulum van skelet- en hartspier

Abstract

QUALITATIVE AND QUANTITATIVE DIFFERENCES BETWEEN THE SARCOPLASMIC RETICULUM OF SKELETAL AND CARDIAC MUSCLE

In this project the problem of the instability of cardiac sarcoplasmic reticulum (CSR) preparations and the mechanisms concerned were investigated. The chosen method was to compare experimental results obtained together with those, given in the literature on the skeletal sarcoplasmic reticulum (SSR) with, experimental results obtained on the CSR and thus to interpret the CSR results. During this comparative study the SSR en CSR were exposed to aging, tryps in digestion, increased temperature, pH changes and solubilization of the membrane by Triton X-100. The interaction between the ATPase protein and Ca²,+ ,ionophores was also investigated.

From the literature and our own results it is clear that CSR preparations are not as stable as SSR preparations. The Ca²+ uptake of CSR in the absence of oxalate is reduced to 50% within 4 days after preparation while SSR remains stable for at least 7 days. The possible contribution of proteolytic enzymes and oxidation to the instability of CSR preparations was investigated with the Aid of phenylmethanesulfonyl flouride (PMSF) which has a strong inhibiting influence on proteolytic enzymes and two antioxidants dithiothreitol (OTT) and, butylated hydroxytoluene (BHT) . It was found that both the proteolytic digestion and oxidation contribute to the instability. From the results obtained ) it is clear that oxidation is the greatest single factor causing the instability. ...