Évolution Temporelle de L'hydrolyse de la Phosphocréatine et de la synthèse d'hexosediphosphate Pendant et Après CINQ Secousses Simples, A O°C, Chez le Sartorius deRana Temporaria, Intoxiqué par l'acide Monoiodoacétique

Abstract

The time course of phosphorylcreatine (PC) splitting at 2°C by Sartorii of Rana Temporaria, poisoned with monoiodoacetic acid, has been followed by chemical analysis. The muscles are frozen at liquid air temperature 0, 10, 15, 30 and 60 seconds after 5 isometric twitches, zero time being taken at the end of the 5th relaxation period. During mechanical activity, the sartorii use 0.87 μmole/g of PC, 0.130 μmole/g of hexose diphosphate (HDP) disappear and a few determinations of ATP show an hydrolysis of 0.33 μmole/g. During the minute which follows, the muscles go on splitting PC at a decreasing rate, 0.825 μmole/g being consumed after 60 seconds. They resynthetize the HDP lost during activity in less than 10 seconds and accumulate afterwards 0.335 μmole/g of the same. Assuming the HDP synthesis to correspond to a loss of an equivalent amount of PC, there is left 0.490 μmole/g of PC to compensate for the ATP not resynthetised during activity and which can be shown to be recovered in 15 or 20 seconds after the end of the last contraction. The post-contractile splitting of PC, detected by chemical analysis, is an argument in favour of the interpretation of the alkalization observed by Dubuisson (1939) and Distèche (1960) and attributed to Lohmann's reaction; it migth be correlated with the negative delayed heat observed by Hartree (1932), D. K. Hill (1940) and A. V. Hill (1961). The heat of PC hydrolysis, in vivo, has been evaluated to – 9.1 Kcal/mole in our experimental conditions, in reasonable agreement with current data.