Based on authors’ previous finding that acute elevations of external osmolality activate

phospholipase C (PLC) in isolated MNC, they further show that the osmotic activation of PLC has a time course and dose-dependence that is consistent with a role in MNC osmosensitivity and that it contributes to the osmotically-evoked increase in non-selective cation current in MNCs through a protein kinase C-dependent pathway. Furthermore, the mechanism underlying osmotic activation of PLC requires an increase in internal Ca2+ that depends on influx through L-type Ca2+ channels. They believe that MNCs possess an osmotically-activated Ca2+-dependent PLC that contributes to the osmotic activation of an N-terminal variant of the TRPV1 channel (ΔN TRPV1) , an important mediator in MNC osmosensitivity and in central osmoregulation.


Questions and discussions:

1.      How does hyperosmotic stimulation increase the activity of PLC? By depolarization-evoked Ca2+ influx through TRPV1 channels-associated L-type Ca2+ channels?

2.      Why are L-type Ca2+ channels (but not other types) important in this process?

3.      Are PLC and its downstream signals form a feedback loop with Ca2+ influx?

4.      What is the subtype of PLC that is specifically involved in the Osmosensation?

5.      What is the mechanism underlying PLC-activation of PLC activation of TRPV1 channels) and M-type K+channels? By phosphorylation or configuration change?

6.      How do osmotically-evoked changes in MNC volume activate a mechanosensitive non-selective cation current?

7.      What is the specific type of PKC that is activated by diacylglycerol (DAG) in osmotic activation of the non-selective cation current?

8.      How did the authors measure the cell volume?

9.      What is the meaning of changes in the capacitance?

10.   What is the usefulness of ramp current analysis?


2018-10-26 Literature analysis

Vimal Bansal & Thomas E. Fisher, Osmotic activation of a Ca2+-dependent phospholipase C pathway that regulates ΔN TRPV1-mediated currents in rat supraoptic neurons,Physiol Rep, 5 (8), 2017, e13259, doi: 10.14814/phy2.13259, Presented by Runsheng Jiao

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