Rabbit neutrophils were stimulated with the chemotactic peptide fMet-Leu-Phe in the presence of the methyltransferase inhibitors homocysteine (HCYS) and 3-deazaadenosine (3-DZA) . HCYS and 3-DZA inhibited chemotaxis, phospholipid methylation, and protein carboxymethylation in a dose-dependent manner . The chemotactic peptide-stimulated release of [t "C]arachidonic acid previously incorporated i...

The mechanism that regulates luteolytic PGF2a secretion as stimulated by oxytocin is thought to involve induction of the inositol (1,4,5)-trisphosphatediacylglycerol second messenger system, which mobilizes intracellular calcium and activates protein kinase C. In Experiment 1, endometrial explants taken from heifers on d 18.5 to 19.5 postestrus had increased PGF2a secretion after treatment with...

Angiotensin II stimulated the breakdown of phosphatidylinositol-4,5-bisphosphate (PIP2) and the generation of inositol trisphosphate (IP,) in cultured rat aortic smooth muscle cells. The decrease in PIP2 and increase in IP, levels were rapid (measurable at 5 seconds; maximum IP, levels at 15 seconds). The time course of these changes was comparable to that of angiotensin Il-induced increases in...

The dense tubular system (DTS) functions to regulate platelet activation by sequestering or releasing calcium, similar to the sarcotubules of skeletal muscle. In resting platelets, the DTS exists as thin elongated membranes. Within 10 seconds of the addition of thrombin, platelets show a major ultrastructural change in their DTS: from the thin elongated form to a rounded vesicular form. These m...