Abstract
The intracellular pathways responsible for maintenance of tone in the lower esophageal sphincter (LES) are not well understood. We show that the protein kinase C (PKC) antagonists (1-(5-isoquinolinesulphonyl)-2- methylpiperazine dihydrochloride) and calphostin C reduce spontaneous resting tone in LES muscle strips, whereas the calmodulin antagonist N-(6-aminohexyl- 5-chloro-1-naphthalenesulfonamide hydrochloride) has no effect, which suggests that LES tone is maintained by a PKC-mediated mechanism. In addition, U73122, an inhibitor of phosphatidylinositol-4,5-bisphosphate (PIP2)-specific phosphotipase C, and D609, an inhibitor of phosphatidycholine-specific phospholipase C, reduced diacylglycerol formation and LES tone in a concentration-dependent manner. Finally, diacylglycerol levels and PKC activity were reduced during relaxation of the LES induced by the inhibitory neurotransmitter vasoactive intestinal peptide. These data suggest that resting LES tone is associated with elevated diacylglycerol levels and PKC activity, which are reduced during relaxation. Diacylglycerol is derived from at least two different sources. Hydrolysis of PIP2 by PIP2- specific phospholipase C produces equimolar amounts of inositol 1,4,5- triphosphate and diacylglycerol, which may interact synergistically to activate PKC and develop tone. Furthermore, PKC-mediated contraction may be augmented by additional diacylglycerol production arising from the hydrolysis of phosphatidylcholine by phosphatidylcholine-specific phospholipase C.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 144-149 |
| Number of pages | 6 |
| Journal | Journal of Pharmacology and Experimental Therapeutics |
| Volume | 277 |
| Issue number | 1 |
| State | Published - Apr 1 1996 |
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All Science Journal Classification (ASJC) codes
- Molecular Medicine
- Pharmacology
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Protein kinase C mediates spontaneous tone in the cat lower esophageal sphincter. / Hillemeier, Craig; Bitar, Khalil N.; Sohn, Uydong; Biancani, Piero.
In: Journal of Pharmacology and Experimental Therapeutics, Vol. 277, No. 1, 01.04.1996, p. 144-149.Research output: Contribution to journal › Article
TY - JOUR
T1 - Protein kinase C mediates spontaneous tone in the cat lower esophageal sphincter
AU - Hillemeier, Craig
AU - Bitar, Khalil N.
AU - Sohn, Uydong
AU - Biancani, Piero
PY - 1996/4/1
Y1 - 1996/4/1
N2 - The intracellular pathways responsible for maintenance of tone in the lower esophageal sphincter (LES) are not well understood. We show that the protein kinase C (PKC) antagonists (1-(5-isoquinolinesulphonyl)-2- methylpiperazine dihydrochloride) and calphostin C reduce spontaneous resting tone in LES muscle strips, whereas the calmodulin antagonist N-(6-aminohexyl- 5-chloro-1-naphthalenesulfonamide hydrochloride) has no effect, which suggests that LES tone is maintained by a PKC-mediated mechanism. In addition, U73122, an inhibitor of phosphatidylinositol-4,5-bisphosphate (PIP2)-specific phosphotipase C, and D609, an inhibitor of phosphatidycholine-specific phospholipase C, reduced diacylglycerol formation and LES tone in a concentration-dependent manner. Finally, diacylglycerol levels and PKC activity were reduced during relaxation of the LES induced by the inhibitory neurotransmitter vasoactive intestinal peptide. These data suggest that resting LES tone is associated with elevated diacylglycerol levels and PKC activity, which are reduced during relaxation. Diacylglycerol is derived from at least two different sources. Hydrolysis of PIP2 by PIP2- specific phospholipase C produces equimolar amounts of inositol 1,4,5- triphosphate and diacylglycerol, which may interact synergistically to activate PKC and develop tone. Furthermore, PKC-mediated contraction may be augmented by additional diacylglycerol production arising from the hydrolysis of phosphatidylcholine by phosphatidylcholine-specific phospholipase C.
AB - The intracellular pathways responsible for maintenance of tone in the lower esophageal sphincter (LES) are not well understood. We show that the protein kinase C (PKC) antagonists (1-(5-isoquinolinesulphonyl)-2- methylpiperazine dihydrochloride) and calphostin C reduce spontaneous resting tone in LES muscle strips, whereas the calmodulin antagonist N-(6-aminohexyl- 5-chloro-1-naphthalenesulfonamide hydrochloride) has no effect, which suggests that LES tone is maintained by a PKC-mediated mechanism. In addition, U73122, an inhibitor of phosphatidylinositol-4,5-bisphosphate (PIP2)-specific phosphotipase C, and D609, an inhibitor of phosphatidycholine-specific phospholipase C, reduced diacylglycerol formation and LES tone in a concentration-dependent manner. Finally, diacylglycerol levels and PKC activity were reduced during relaxation of the LES induced by the inhibitory neurotransmitter vasoactive intestinal peptide. These data suggest that resting LES tone is associated with elevated diacylglycerol levels and PKC activity, which are reduced during relaxation. Diacylglycerol is derived from at least two different sources. Hydrolysis of PIP2 by PIP2- specific phospholipase C produces equimolar amounts of inositol 1,4,5- triphosphate and diacylglycerol, which may interact synergistically to activate PKC and develop tone. Furthermore, PKC-mediated contraction may be augmented by additional diacylglycerol production arising from the hydrolysis of phosphatidylcholine by phosphatidylcholine-specific phospholipase C.
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UR - http://www.scopus.com/inward/citedby.url?scp=0030439671&partnerID=8YFLogxK
M3 - Article
C2 - 8613911
AN - SCOPUS:0030439671
VL - 277
SP - 144
EP - 149
JO - Journal of Pharmacology and Experimental Therapeutics
JF - Journal of Pharmacology and Experimental Therapeutics
SN - 0022-3565
IS - 1
ER -