The labelling in vitro by [32P]phosphate of phosphatidic acid and phosphatidylinositol in synaptosomes from guinea-pig brain was studied. Acetylcholine increased the labelling and evidence is provided that pre-synaptic muscarinic receptors are involved. The increase was not seen in the presence of EGTA. Experiments with various calcium buffers indicated that concentrations of greater than 10−7 M free Ca2+ are required in the incubation medium for this phospholipid effect. A similar muscarinic effect in parotid gland is unaffected by EGTA. It is suggested that, in the parotid, postsynaptic receptors mediate increased phosphatidylinositol labelling and increased availability of Ca2+ for stimulus-secretion coupling. Presynaptic receptors similarly mediate increased labelling, which differs in being sensitive to EGTA and associated with decreased availability of Ca2+
A calcium requirement for the phosphatidylinositol response floowing activation of presynaptic muscarinic receptors.
ORLACCHIO, Aldo
1979
Abstract
The labelling in vitro by [32P]phosphate of phosphatidic acid and phosphatidylinositol in synaptosomes from guinea-pig brain was studied. Acetylcholine increased the labelling and evidence is provided that pre-synaptic muscarinic receptors are involved. The increase was not seen in the presence of EGTA. Experiments with various calcium buffers indicated that concentrations of greater than 10−7 M free Ca2+ are required in the incubation medium for this phospholipid effect. A similar muscarinic effect in parotid gland is unaffected by EGTA. It is suggested that, in the parotid, postsynaptic receptors mediate increased phosphatidylinositol labelling and increased availability of Ca2+ for stimulus-secretion coupling. Presynaptic receptors similarly mediate increased labelling, which differs in being sensitive to EGTA and associated with decreased availability of Ca2+I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
