Ca2+ regulation of the contractile apparatus in canine gastric smooth muscle.

Ozaki, Hiroshi; Gerthoffer, William T.; Hori, Masaru; Karaki, Hideaki; Sanders, Kenton M.; Publicover, Nelson G.

doi:10.1113/jphysiol.1993.sp019457

Cited by 22 publications

(16 citation statements)

References 48 publications

(41 reference statements)

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“…Our results are consistent with the hypothesis that sensitization of the contractile elements to Ca 2ϩ occurs following PKC activation in smooth muscles (24,33,36,42). We demonstrated that PKC-␦ translocates to the cytoskeleton following exposure to phorbol esters and that these compounds do not evoke smooth muscle contractions.…”

Section: Pkc-␦ Interactions With the Cytoskeletonsupporting

confidence: 92%

PKC δ-isoform translocation and enhancement of tonic contractions of gastrointestinal smooth muscle

Poole¹,

Furness²

2007

American Journal of Physiology-Gastrointestinal and Liver Physi

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Section: Pkc-␦ Interactions With the Cytoskeletonsupporting

confidence: 92%

PKC δ-isoform translocation and enhancement of tonic contractions of gastrointestinal smooth muscle

Poole¹,

Furness²

2007

American Journal of Physiology-Gastrointestinal and Liver Physi

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“…Taken together, the above findings lead us to conclude that the suppressive effects of PDBu on stomach fundus smooth muscle tone are due to reduced Ca 2+ -channel activity, rather than to reduced PI turnover. Although we did not investigate the effects of PDBu on Ca 2+ movement or electrophysiological Ca 2+ current, this speculation is supported by the finding that addition of PDBu to intact canine gastric smooth muscles reduced Ca 2+ transients and contractions (Ozaki et al, 1993). …”

Section: Discussionmentioning

confidence: 87%

Effect of phorbol 12,13-dibutyrate on smooth muscle tone in rat stomach fundus

Matsumoto

Nishiyama

Kobayashi

et al. 2005

J. Smooth Muscle Res.

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We investigated the effects of phorbol 12,13-dibutyrate (PDBu), a typical protein kinase C (PKC) activator, on smooth muscle tone in the rat stomach fundus. In 5-hydroxytriptamine (5-HT)-precontracted stomach fundus strips, PDBu induced dosedependent relaxation, but 4α-phorbol 12,13-didecanoate, a phorbol ester that does not activate PKC, did not induce relaxation. A PDBu-induced dose-dependent relaxation was also observed in strips precontracted with platelet-activating factor (PAF), carbachol, or 60 mM K + . In stomach fundus strips pretreated with PDBu, the contractile responses to 5-HT and PAF were completely blocked, but those induced by carbachol and endothelin-1 (ET-1) were only partially inhibited. In stomach fundus strips preincubated with carbachol in Ca 2+ -free medium, the Ca 2+ -induced contraction was decreased by preincubation with PDBu. In strips preincubated with 5-HT, PAF, or ET-1 in Ca 2+ -free medium, Ca 2+ -induced contractions were greatly inhibited by pretreatment with PDBu.These results suggest that in rat stomach fundus strips, PDBu-induced relaxation is mediated by activation of PKC. We speculate that a major factor mediating the relaxant action of PDBu in rat stomach fundus smooth muscle is represented by a reduction in Ca 2+ influx via an inhibition of Ca 2+ channels.

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“…The augmentation of contraction may be explained by an increase in Ca2+ sensitivity, as it has been shown that phorbol esters increase Ca2+ sensitivity of the contractile elements in vascular and intestinal smooth muscles (Itoh et al, 1988;Nishimura & Van Breemen, 1989;Sato et al, 1992;Ozaki et al, 1993). In order to confirm this possibility, we examined the effect of DPB on the Ca2+-induced contraction in permeabilized muscle strips.…”

Section: Discussionmentioning

confidence: 87%

Contractile and relaxant effects of phorbol ester in the intestinal smooth muscle of guinea‐pig taenia caeci

Mitsui

Karaki

1993

British J Pharmacology

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1 Effects of phorbol esters on the cytosolic Ca2" level ([Ca2+]j) and muscle tension in the intestinal smooth muscle of guinea-pig taenia caeci were examined.2 12-Deoxyphorbol 13-isobutyrate (DPB, 1 gM) did not change the [Ca2+]i and tension in resting muscle.3 In high K+-stimulated muscle, 1 gM DPB transiently augmented the contraction and decreased [Ca2+]. 12-Deoxyphorbol 13-isobutyrate 20-acetate (1 JAM) and phorbol 12, 13-dibutyrate (1 JAM) showed similar effects to DPB whereas phorbol 12-myristate 13-acetate (1 JM) and phorbol 12, 13-didecanoate (1 JM) were ineffective.4 DPB (1 JM) inhibited both [Ca2+]i and tension stimulated by 300 nM carbachol or 3 JAM histamine. In the presence of a higher concentration of carbachol (1 JM), DPB decreased [Ca2+]i and transiently increased muscle tension. 5 In the muscle strips permeabilized with bacterial a-toxin, 1 JAM DPB shifted the Ca2+-tension curve to the left. An inhibitor of protein kinase C, H-7 (30 JAM), inhibited the effect of DPB. 6 DPB did not change the high K+-induced contraction in the muscle strips pretreated with 3 JAM phorbol 12-myristate 13-acetate for 24 h. 7 These results suggest that activation of protein kinase C has dual effects; it augments contraction by increasing the Ca2+ sensitivity of the contractile elements and it inhibits contraction by decreasing [Ca2+ i.

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Ca2+ regulation of the contractile apparatus in canine gastric smooth muscle.

Cited by 22 publications

References 48 publications

PKC δ-isoform translocation and enhancement of tonic contractions of gastrointestinal smooth muscle

PKC δ-isoform translocation and enhancement of tonic contractions of gastrointestinal smooth muscle

Effect of phorbol 12,13-dibutyrate on smooth muscle tone in rat stomach fundus

Contractile and relaxant effects of phorbol ester in the intestinal smooth muscle of guinea‐pig taenia caeci

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