PubMed Health⌕ Search

Biomedical subjects

P Guilbault

Publications and source records attributed to P Guilbault.

At least 37 records · Page 2Linked to original sources
PubMed1978

[Effects of hypertonic solutions on the excitation-contraction coupling of the skeletal muscle fibre of the crab. II. Ultrastructural aspects (author's transl)].

Experiments were performed to investigate the modifications of electrical activity and the loss of contraction by examination of the ultrastructure. These alterations were obtained with a control physiological solution (artificial sea water, ASW) which was made hypertonic by adding sucrose, glycerol, choline chloride or urea. 1. Under these conditions, the ultrastructural results show that: a) all those substances induce a modification of the coupling junction (either diad or triad). This modification can explain the inhibition of the mechanical phenomenon; b) sucrose (Figs. 6C and 6D) and glycerol (Figs. 4A and 4B) induce alterations of the surface membrane and of the tubular system (less important with glycerol). They can explain the decrease of the resting potential and the abolishment or the modification of the action potential; c) in contrast, choline chloride (Figs. 7A to 7E) and urea (Figs. 9A to 9F) only modify the organisation of the coupling junction. The action potential is maintained. 2. A short exposure of the fibre in an isotonic sucrose solution (Figs. 5A to 5D) deeply modifies the tubular system, particularly, in cutting it off from the sarcolemma. 3. Choline chloride and urea produce similar changes in the ultrastructure but as urea is not ionized, it can be added to the ASW to investigate the electrical phenomenon which cannot be modified by contraction.

Animals↗
PubMed1975

[Inward currents of crab striated muscle fiber measured by the voltage clamp technique with microelectrodes].

Membrane currents during depolarisation steps were determined by a method in which three electrodes were inserted near the end of the crab's striated muscular fibre. The value of the reversal potential for the early current appears to be consistent with the calcium equilibrium potential. This early transient inward current is abolished by manganese. The value of about +120mV is consistent with the level of internal free Ca++ ions, as generally tested by different authors.

Animals↗
PubMed1975

[The effect of cations on the contraction of myofibrils in the striated muscles of crabs].

Myofilaments have been prepared from crab legs according to a technique derived from that of F.J. Julian (1971). Tension variations have been recorded while the isolated fiber was submitted to the action of different saline solutions. As expected, it could be confirmed that the tension mainly depends on the content in Ca++ and Mg++ ions and in ATP. Our results have also shown that monovalent ions (Na+ and K+) when added separately, produce an important tension increase wheras their simultaneous addition or withdrawal modifies the tension only slightly.

Adenosine Triphosphate↗