THE SUBCELLULAR LOCALIZATION OF CARBAMYLCHOLINE‐STIMULATED PHOSPHATIDYL INOSITOL TURNOVER IN RAT CEREBRAL CORTEX IN VIVO

Abstract

Abstract— The intraventricular injection of 40 μCi of 32Pi (carrier free) into adult rats resulted in maximum incorporation of 32Pi into the phosphatidyl inositol of the whole cortex after 20 h. A further intraventricular injection of 2 nmol carbamylcholine plus 0.02 nmol eserine resulted in a 23% decrease in the specific activity of phosphatidyl inositol after 20 min. The specific radioactivities of phosphatidyl choline, phosphatidyl ethanolarmine and phosphatidyl serine were not changed. Cerebral cortex from rats treated in this way was subjected to an extensive subcellular fractionation. It was found that the specific radioactivity of the phosphatidyl inositol of the synaptic vesicle fraction showed a reduction of 60%. No other fractions showed effects of this magnitude.

Phosphatidate as a Molecular Link Between Depolarization and Neurotransmitter Release in the Brain

“…Rates of karyotypic evolution vary tremendously both within and among major taxa of animals and plants (1)(2)(3)(4)(5)(6)(7)(8)(9). Accurate determinations of such rates are desirable for testing alternative models of chromosomal evolution because most models attempt to expln why the rates of chromosomal rearrangement incorporation differ among taxa.…”

“…However, the electrical stimulation of synaptosomal beds (4) or the application of acetylcholine to synaptosome preparations (5) results in a significant increase in the incorporation of 32p into PA. Generally, changes in PI under these conditions are variable. Other studies have shown that the initial event in the PA effect is the breakdown of PI, probably to the D-1,2-sn-diglyceride, which is then converted to PA (6).…”

Phospholipids in Synaptic Function

“…LAPETINA et al (1976) had reached similar conclusions. This cholinergic phosphatidylinositol effect has been shown in uiuo as well as in vitro (LUNT & PICKARD, 1975).…”

“…Though loss of labelled phosphatidylinositol was not seen in these experiments, other synaptosomal studies have shown it, e.g. studies in uiuo with carbamylcholine (LUNT & PICKARD, 1975) and electrical stimulation of synaptosomes labelled in uiuo (PICKARD & HAWTHORNE, 1978~).…”

Production of diglyceride from phosphatidylinositol in activated human platelets.

“…In tissues such as pancreas, cerebral cortex, and parotid gland, stimulation by acetylcholinie elicits a breakdown of PI (3)(4)(5). The secretory response of platelets is essenitially complete within 30 s (6).…”