Occurrence of platelet-activating factor (PAF) in normal rat stomach and alteration of PAF level by water immersion stress.
We detected platelet-activating substance in gastrointestinal areas, which was confirmed to be platelet-activating factor (PAF) on the basis of the following findings: 1) it comigrated with authentic PAF on thin-layer chromatography; 2) it did not aggregate PAF-desensitized platelets; and 3) its activity was completely antagonized by the receptor antagonists CV3988 and L-652,731. The level of PAF was determined with a bioassay method based on the release of [3H]serotonin from washed rabbit platelets. In the normal rat stomach, the level of PAF was high in the antrum (940 +/- 200 nmol PAF/mol phosphorus of original phospholipids), especially in the antral mucosa (1801 +/- 426 nmol/mol phosphorus of original phospholipids). The stomach PAF level was significantly altered by water immersion stress. Stress for a period of 1 h was associated with a decrease in the antral PAF level to 39 +/- 7% of that of untreated controls. This low PAF level persisted during stress. On the other hand, in the corpus, stress for periods of 1 and 3 h was associated with decreases in the PAF content, and further stress (7 h) resulted in restoration of the PAF level to normal. Furthermore, 7 h of stress was associated with distinct hemorrhagic lesions, which were prevented by CV3988 infused i.v. before the stress. This is the first report of an association between a decrease of the endogenous PAF level in animal tissues and tissue damage.
Sugatani
J
J
Department of Medical Chemistry, Kansai Medical School, Osaka, Japan.
Fujimura
K
K
Miwa
M
M
Mizuno
T
T
Sameshima
Y
Y
Saito
K
K
D043203:1-Alkyl-2-acetylglycerophosphocholine Esterase; D000818:Animals; D007101:Immersion / Q000503:physiopathology*; D008297:Male; D010741:Phospholipases A / Q000378:metabolism; D010742:Phospholipid Ethers / Q000494:pharmacology; D010972:Platelet Activating Factor / Q000502:physiology*; D010974:Platelet Aggregation; D051381:Rats; D012701:Serotonin / Q000378:metabolism; D013270:Stomach / Q000502:physiology*; D013276:Stomach Ulcer / Q000503:physiopathology*; D013312:Stress, Physiological / Q000503:physiopathology*
D010742:Phospholipid Ethers; D010972:Platelet Activating Factor; D012701:Serotonin; C037913:CV 3988; D010741:Phospholipases A; D043203:1-Alkyl-2-acetylglycerophosphocholine Esterase