L- and DL-carnitine induce tetanic fade in rat neuromuscular preparation
Braz. j. med. biol. res
;
36(9): 1255-1262, Sept. 2003. ilus
Article
in English
| LILACS
| ID: lil-342846
ABSTRACT
Carnitine, a structurally choline-like metabolite, has been used to increase athletic performance, although its effects on neuromuscular transmission have not been investigated. It is present in skeletal muscle and its plasma levels are about 30 to 90 æM. Using rat phrenic nerve diaphragm preparations indirectly and directly stimulated with high rate pulses, D-carnitine (30 and 60 æM), L-carnitine (60 æM) and DL-carnitine (60 æM) were shown to induce tetanic fade (D-carnitine = 19.7 ± 3.1 percent, N = 6; L-carnitine = 16.6 ± 2.4 percent, N = 6; DL-carnitine = 14.9 ± 2.1 percent, N = 6) without any reduction of maximal tetanic tension. D-carnitine induced tetanic fade in neuromuscular preparations previously paralyzed with d-tubocurarine and directly stimulated. The effect was greater than that obtained by indirect muscle stimulation. Furthermore, previous addition of atropine (20 to 80 æM) to the bath did not reduce carnitine isomer-induced tetanic fade. In contrast to D-carnitine, the tetanic fade induced by L- and DL-carnitine was antagonized by choline (60 æM). The combined effect of carnitine isomers and hemicholinium-3 (0.01 nM) was similar to the effect of hemicholinium-3 alone. The data suggest that L- and DL-carnitine-induced tetanic fade seems to depend on their transport into the motor nerve terminal
Full text:
Available
Index:
LILACS (Americas)
Main subject:
Phrenic Nerve
/
Diaphragm
/
Carnitine
/
Synaptic Transmission
/
Muscle Neoplasms
/
Muscle Contraction
Limits:
Animals
Language:
English
Journal:
Braz. j. med. biol. res
Journal subject:
Biology
/
Medicine
Year:
2003
Type:
Article
/
Project document
Affiliation country:
Brazil
Institution/Affiliation country:
Universidade Estadual de Maringá/BR
/
Universidade de Säo Paulo/BR
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