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Effects of cannabinoids on caffeine contractures in slow and fast skeletal muscle fibers of the frog.

Huerta M, Ortiz-Mesina M, Trujillo X, Sánchez-Pastor E, Vásquez C, Castro E, Velasco R, Montoya-Pérez R, Onetti C - J. Membr. Biol. (2009)

Bottom Line: This ACPA effect was not statistically significant with respect to the reduction in tension in slow muscle fibers.Moreover, we detected the presence of mRNA for the cannabinoid CB(1) receptor on fast and slow skeletal muscle fibers, which was significantly higher in fast compared to slow muscle fiber expression.In conclusion, our results suggest that in the slow and fast muscle fibers of the frog cannabinoids diminish caffeine-evoked tension through a receptor-mediated mechanism.

View Article: PubMed Central - PubMed

Affiliation: Unidad de Investigación Dr. Enrico Stefani del, Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Colonia Villa San Sebastián, Colima, México.

ABSTRACT
The effect of cannabinoids on caffeine contractures was investigated in slow and fast skeletal muscle fibers using isometric tension recording. In slow muscle fibers, WIN 55,212-2 (10 and 5 microM) caused a decrease in tension. These doses reduced maximum tension to 67.43 +/- 8.07% (P = 0.02, n = 5) and 79.4 +/- 14.11% (P = 0.007, n = 5) compared to control, respectively. Tension-time integral was reduced to 58.37 +/- 7.17% and 75.10 +/- 3.60% (P = 0.002, n = 5), respectively. Using the CB(1) cannabinoid receptor agonist ACPA (1 microM) reduced the maximum tension of caffeine contractures by 68.70 +/- 11.63% (P = 0.01, n = 5); tension-time integral was reduced by 66.82 +/- 6.89% (P = 0.02, n = 5) compared to controls. When the CB(1) receptor antagonist AM281 was coapplied with ACPA, it reversed the effect of ACPA on caffeine-evoked tension. In slow and fast muscle fibers incubated with the pertussis toxin, ACPA had no effect on tension evoked by caffeine. In fast muscle fibers, ACPA (1 microM) also decreased tension; the maximum tension was reduced by 56.48 +/- 3.4% (P = 0.001, n = 4), and tension-time integral was reduced by 57.81 +/- 2.6% (P = 0.006, n = 4). This ACPA effect was not statistically significant with respect to the reduction in tension in slow muscle fibers. Moreover, we detected the presence of mRNA for the cannabinoid CB(1) receptor on fast and slow skeletal muscle fibers, which was significantly higher in fast compared to slow muscle fiber expression. In conclusion, our results suggest that in the slow and fast muscle fibers of the frog cannabinoids diminish caffeine-evoked tension through a receptor-mediated mechanism.

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A 1% agarose gel showing electrophoresis results for RT-PCR analysis of CB1 receptor. Lane 1, HindIII; lane 2, nontransfected HEK293 cells; lane 3, transfected HEK293 cells; lane 4, frog fast extensor digitorum longus muscle; lane 5, frog slow cruralis muscle; lane 6, HindIII. All lanes contained actin and the CB1 primers
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Fig1: A 1% agarose gel showing electrophoresis results for RT-PCR analysis of CB1 receptor. Lane 1, HindIII; lane 2, nontransfected HEK293 cells; lane 3, transfected HEK293 cells; lane 4, frog fast extensor digitorum longus muscle; lane 5, frog slow cruralis muscle; lane 6, HindIII. All lanes contained actin and the CB1 primers

Mentions: CB1 receptors are broadly localized in the central nervous system and in some peripheral tissues, but the presence of these kinds of receptors in skeletal muscle has not been determined. The presence of CB1 receptor mRNA was determined in frog fast and slow skeletal muscle fibers. Fast muscle fibers were obtained from the extensor digitorum longus muscle and slow muscle fibers, from tonic bundles of cruralis muscle. In Fig. 1, lane 2 shows untransfected HEK293 cells (negative control). Lane 3 shows HEK293 cells transfected with CB1 (positive control). The expected size for CB1 was 579 bp. Lanes 4 and 5 show the expression of CB1 receptors in fast and slow skeletal muscle fibers, respectively. As can be seen, CB1 expression is very abundant in fast skeletal muscle fibers (lane 4) as its expression is comparable with induced expression in HEK cells (lane 3). On the other hand, although to a lesser extent, slow muscle fibers also express mRNA for CB1, shown as a faint but visible band in lane 5. Expression of β-actin was used as a control for RNA quality. The relationship to the mRNA expression for CB1/β-actin was 0.99 ± 0.03 for fast muscle fibers and 0.51 ± 0.10 for slow muscle fibers. The difference was statistically significant (P = 0.002, n = 6). Thus, CB1 receptors are present in both fast and slow skeletal muscle fibers of the frog.Fig. 1


Effects of cannabinoids on caffeine contractures in slow and fast skeletal muscle fibers of the frog.

Huerta M, Ortiz-Mesina M, Trujillo X, Sánchez-Pastor E, Vásquez C, Castro E, Velasco R, Montoya-Pérez R, Onetti C - J. Membr. Biol. (2009)

A 1% agarose gel showing electrophoresis results for RT-PCR analysis of CB1 receptor. Lane 1, HindIII; lane 2, nontransfected HEK293 cells; lane 3, transfected HEK293 cells; lane 4, frog fast extensor digitorum longus muscle; lane 5, frog slow cruralis muscle; lane 6, HindIII. All lanes contained actin and the CB1 primers
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2697372&req=5

Fig1: A 1% agarose gel showing electrophoresis results for RT-PCR analysis of CB1 receptor. Lane 1, HindIII; lane 2, nontransfected HEK293 cells; lane 3, transfected HEK293 cells; lane 4, frog fast extensor digitorum longus muscle; lane 5, frog slow cruralis muscle; lane 6, HindIII. All lanes contained actin and the CB1 primers
Mentions: CB1 receptors are broadly localized in the central nervous system and in some peripheral tissues, but the presence of these kinds of receptors in skeletal muscle has not been determined. The presence of CB1 receptor mRNA was determined in frog fast and slow skeletal muscle fibers. Fast muscle fibers were obtained from the extensor digitorum longus muscle and slow muscle fibers, from tonic bundles of cruralis muscle. In Fig. 1, lane 2 shows untransfected HEK293 cells (negative control). Lane 3 shows HEK293 cells transfected with CB1 (positive control). The expected size for CB1 was 579 bp. Lanes 4 and 5 show the expression of CB1 receptors in fast and slow skeletal muscle fibers, respectively. As can be seen, CB1 expression is very abundant in fast skeletal muscle fibers (lane 4) as its expression is comparable with induced expression in HEK cells (lane 3). On the other hand, although to a lesser extent, slow muscle fibers also express mRNA for CB1, shown as a faint but visible band in lane 5. Expression of β-actin was used as a control for RNA quality. The relationship to the mRNA expression for CB1/β-actin was 0.99 ± 0.03 for fast muscle fibers and 0.51 ± 0.10 for slow muscle fibers. The difference was statistically significant (P = 0.002, n = 6). Thus, CB1 receptors are present in both fast and slow skeletal muscle fibers of the frog.Fig. 1

Bottom Line: This ACPA effect was not statistically significant with respect to the reduction in tension in slow muscle fibers.Moreover, we detected the presence of mRNA for the cannabinoid CB(1) receptor on fast and slow skeletal muscle fibers, which was significantly higher in fast compared to slow muscle fiber expression.In conclusion, our results suggest that in the slow and fast muscle fibers of the frog cannabinoids diminish caffeine-evoked tension through a receptor-mediated mechanism.

View Article: PubMed Central - PubMed

Affiliation: Unidad de Investigación Dr. Enrico Stefani del, Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Colonia Villa San Sebastián, Colima, México.

ABSTRACT
The effect of cannabinoids on caffeine contractures was investigated in slow and fast skeletal muscle fibers using isometric tension recording. In slow muscle fibers, WIN 55,212-2 (10 and 5 microM) caused a decrease in tension. These doses reduced maximum tension to 67.43 +/- 8.07% (P = 0.02, n = 5) and 79.4 +/- 14.11% (P = 0.007, n = 5) compared to control, respectively. Tension-time integral was reduced to 58.37 +/- 7.17% and 75.10 +/- 3.60% (P = 0.002, n = 5), respectively. Using the CB(1) cannabinoid receptor agonist ACPA (1 microM) reduced the maximum tension of caffeine contractures by 68.70 +/- 11.63% (P = 0.01, n = 5); tension-time integral was reduced by 66.82 +/- 6.89% (P = 0.02, n = 5) compared to controls. When the CB(1) receptor antagonist AM281 was coapplied with ACPA, it reversed the effect of ACPA on caffeine-evoked tension. In slow and fast muscle fibers incubated with the pertussis toxin, ACPA had no effect on tension evoked by caffeine. In fast muscle fibers, ACPA (1 microM) also decreased tension; the maximum tension was reduced by 56.48 +/- 3.4% (P = 0.001, n = 4), and tension-time integral was reduced by 57.81 +/- 2.6% (P = 0.006, n = 4). This ACPA effect was not statistically significant with respect to the reduction in tension in slow muscle fibers. Moreover, we detected the presence of mRNA for the cannabinoid CB(1) receptor on fast and slow skeletal muscle fibers, which was significantly higher in fast compared to slow muscle fiber expression. In conclusion, our results suggest that in the slow and fast muscle fibers of the frog cannabinoids diminish caffeine-evoked tension through a receptor-mediated mechanism.

Show MeSH
Related in: MedlinePlus