Changes in ATPase and SDH reactions of the rat extrafusal and intrafusal muscle fibres after preincubations at different pH

Abstract

The dependence of adenosine-triphosphatase (ATPase) and succinic dehydrogenase (SDH) histochemical reactions on the pH of the preincubation medium was studied in serial cross sections of 1- to 6-month-old rat extensor digitorum longus (EDL) and soleus (SOL) muscles. The use of a wide spectrum of pH values confirmed the previous results showing that: (1) according to their ATPase and SDH reactions 3 types of extrafusal muscle fibres, i.e., fast-twitch glycolytic (FG), fast-twitch oxidative-glycolytic (FOG) and slow-twitch oxidative (SO) and 3 types of intrafusal muscle fibres, i.e. typical and intermediate nuclear bag fibres and nuclear chain fibres were observed; (2) only acid preincubation (pH 4.35) is necessary to demonstrate the reversal of the ATPase reaction; while (3) alkali preincubation (pH 10.4) does not provide any new important information as compared with ATPase without preincubation. Furthermore, it was shown that: (4) fast-twitch muscle fibres exhibited high ATPase activity on preincubations at pH 4.9 to 10.4, slow-twitch fibres had very high ATPase activity on preincubation at pH 4.3 and 4.5; (5) after preincubation at pH 4.5 two types of FOG fibres were observed, differing in their ATPase activity; (6) in both muscles there were fibres with intermediate ATPase activity both after acid and/or alkali preincubations; (7) the intrafusal muscle fibres exhibited some specific characteristics when compared with extrafusal fibres. In contrast to the ATPase reactions, SDH activity was decreased equally, in both extra- and intrafusal fibres, with increasing acidity and alkality of the preincubation medium.

Characterization of Fiber Types in Different Muscles of the Hindlimb in Female Weanling and Adult Wistar Rats

“…Another important characteristic identified in our study of adult soleus muscle was the presence of TIIADF and TIIDF. The hybrid and pure fibers containing MHCIId form were only described by spectrophotometer [30] which aided our findings, although there are no reports of this type of fiber by mATPase analysis in the literature.…”

Expression of myosin heavy chain isoforms and myogenesis of intrafusal fibres in rat muscle spindles

“…The mATPase activity is not uniform along the length of the intrafusal fibres ( Fig. 3) in rat (Khan and Soukup, 1988;Kucera et al, 1978;Soukup, 1976;Soukup et al, 1979;Yellin, 19741, cat (Banks et al, 1977;Kucera, 19811, and human muscle spindles (Eriksson and Thornell, 1985;Eriksson et al, 1993;Kucera and Dorovini-Zis, 1979;Soukup et al, 1992;Thornell et al, 1988a).…”

Slow to fast muscle transformation following heterochronous isotransplantation is influenced by host thyroid hormone status

“…*p ≤ 0.05 compared to the EU rats that in EU rats the regenerated and reinnervated SOL (GRAFT), a typical slow muscle with a strong predominance of type 1 fibers over a low and variable number of type 2A fibers but lacking type 2X and 2B fibers, always developed into a fast-like muscle after grafting into fast EDLh muscle, which expresses MyHC-2x and MyHC-2b as the prevailing isoforms. Interestingly, at the time of transplantation and animal age of 3-4 weeks, the SOL muscle had not completely differentiated into a slow muscle as it contained almost 40 % of type 2A and 1/2A fibers apart from the prevailing type 1, as demonstrated by mATPase histochemistry (Soukup et al 1979). Despite this, the difference between the fiber type proportions of GRAFT and SOL of young 3-week to 4-week-old naive rats was significant.…”