Variation of acid-soluble sulphydryl groups during liver regeneration.

Abstract

THE role of acid-soluble -SH compounds in mitosis has been a subject of interest since the work of Rapkine (1931) showed that the "glutathione" content of sea-urchin eggs increased markedly upon fertilisation and underwent cyclic variation during mitosis. Subsequent work by Sakai and Dan (1959) showed that the thiol compound involved was not glutathione but a small polypeptide. The consequences and interpretations of these results have been extensively discussed by Mazia (1959, 1961). Swann (1957Swann ( , 1958 postulated that the energy requirements of mitosis are met by a reservoir of a specific mitotic fuel and tentatively suggested that a thiol-ester would satisfy the requirements of the fuel substance. The observed cyclic fluctuations in -SH would then reflect the filling and discharge of the energy reservoir.It is known that the acid-soluble -SH level of rat liver is elevated during regeneration and the question arises whether or not the increase may be directed towards the building up of a thiol-ester pool. Such an increase in -SH level has been reported by several groups of workers, who are in general agreement that a rise of between 20% and 100% occurs by 24 hours after partial hepatectomy (Christiansen et al., 1948;Ferrari and Harkness, 1954;Bahr, 1957;Hopsu and Harkonnen, 1960; Millard Smith, 1962).These results, however, are not complete since, in most cases, measurements were made at intervals of 12 hours or more, and were too few in number to enable an assessment to be made of how the -SH rise compared to the normal variation to be expected from one animal to another.The period of greatest biochemical interest in liver regeneration is the first thirty hours, culminating in a wave of nearly synchronous mitoses. It was therefore decided to measure acid-soluble -SH levels at two hour intervals during this period in order to determine more precisely the time of the -SH rise, and to look for any smaller fluctuations in level which might reflect the formation of a pool of thiol-ester. Efforts have also been made to characterise the peptide(s) involved. Throughout this paper the term " -SH level " refers to the acid-soluble fraction. MATERIALS AND METHODSAll the animals used were male black and white rats weighing between 210 and 340 g. Partial hepatectomy was performed by the method of Higgins and Anderson (1931) during ether anaesthesia. Rats were fed ad libitum, before and after partial hepatectomy and were kept at a constant temperature of 24°C.

A study of soluble protein and sulfhydryl levels in the rat liver during rapid normal and premalignant growth

“…The increase noted in the sulfhydryl level of soluble liver proteins following partial hepatectomy is in agreement with the data of Hopsu and Harkonen (1960) who showed by histochemical methods that there is an overall increase in the actual number of sulfhydryl groups in total liver protein during regeneration, and with the findings of Fraser and Cater (1967) that the level of acid-soluble -SH during liver regeneration in the rat increases above normal by 12 hours after hepatectomy and remains elevated until after the first wave of mitosis at 28-30 hours.…”

Studies of nuclei separated by zonal centrifugation from liver of rats treated with thioacetamide

“…It may be relevant that thioacetamide has the property of breaking dormancy of tubers, and it was suggested that thiol compounds may inactivate the growth-inhibitory unsaturated ketonic substances by addition reactions (Sexton, 1949). The amount of acid-soluble thiol compounds increases during the late pre-replicative period of liver regeneration in the rat (Fraser & Cater, 1967).…”