Mechanical stimulation of skeletal muscle generates lipid-related second messengers by phospholipase activation
✍ Scribed by Herman H. Vandenburgh; Janet Shansky; Patricia Karlisch; Rosa Lopez Solerssi
- Publisher
- John Wiley and Sons
- Year
- 1993
- Tongue
- English
- Weight
- 958 KB
- Volume
- 155
- Category
- Article
- ISSN
- 0021-9541
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✦ Synopsis
Abstract
Repetitive mechanical stimulation of cultured avian skeletal muscle increases the synthesis of prostaglandins (PG) E~2~ and F~2α~ which regulate protein turnover rates and muscle cell growth. These stretch‐induced PG increases are reduced in low extracellular calcium medium and by specific phospholipase inhibitors. Mechanical stimulation increases the breakdown rate of ^3^H‐arachidonic acid labelled phospholipids, releasing free ^3^H‐arachidonic acid, the rate‐limiting precursor of PG synthesis. Mechanical stimulation also increases ^3^H‐arachidonic acid labelled diacylglycerol formation and intracellular levels of inositol phosphates from myo‐[2‐^3^H]inositol labelled phospholipids. Phospholipase A~2~ (PLA~2~), phosphatidylinositol‐specific phospholipase C (PLC), and phospholipase D (PLD) are all activated by stretch. The stretch‐induced increases in PG production, ^3^H‐arachidonic acid labelled phospholipid breakdown, and ^3^H‐arachidonic acid labelled diacylglycerol formation occur independently of cellular electrical activity (tetrodotoxin insensitve) whereas the formation of inositol phosphates from myo‐[2‐^3^H]inositol labelled phospholipids is dependent on cellular electrical activity. These results indicate that mechanical stimulation increases the lipid‐related second messengers arachidonic acid, diacylglycerol, and PG through activation of specific phospholipases such as PLA~2~ and PLD, but not by activation of phosphatidylinositol‐specific PLC. © 1993 Wiley‐Liss, Inc.