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Presynaptic organization of CaV2 channels with specific vesicle pools in SCG vs rat tail artery
Author(s) -
Kalkhoran Somayeh Mojard,
Walia Jag,
Gershome Cynthia,
Chow Sarah HJ,
Poburko Damon
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.847.6
Subject(s) - gene isoform , vesicle , norepinephrine , synaptic vesicle , sympathetic nervous system , superior cervical ganglion , biology , microbiology and biotechnology , medicine , chemistry , anatomy , endocrinology , dopamine , biochemistry , blood pressure , gene , membrane
Peripheral sympathetic nerves co‐release multiple neurotransmitters to modulate the activity of their target organ, for example mediating physiological regulation of cardiac contractility and systemic vascular tone. However, the release of “co‐released” transmitters like norepinephrine (NE) and ATP can be differentially regulated, for example by relying on specific isoforms of voltage‐gated Ca2+ channels (CaV), and we previously reported that NE‐ and ATP‐containing vesicles segregate in pools that preferentially co‐localize with specific CaV2 isoforms in rat tail artery. Whether this observation generalizes to other sympathetic nerves is not known, but it is of fundamental importance to understanding the molecular biology of sympathetic co‐release. OBJECTIVE To determine whether specific isoforms of CaV selectively associate with pools of vesicles enriched with transporters for NE or ATP in multiple peripheral sympathetic nerves. METHODS We performed epifluorescence imaging of intact rat tail artery and cultured superior cervical ganglia (SCG) neurons, comparing the localization and intensity correlation of CaV2.1, CaV2.2, and CaV2.3 with vesicle markers for NE (VMAT2) and ATP (VNUT/SlC17A) containing vesicles or suitable surrogate markers. RESULTS We confirmed that VMAT2 and VNUT are often but not always found in the same varicosities. While VMAT2 is broadly distributed in varicosity, VNUT localizes as discrete puncta at the perimeter of varicosity and does not co‐localize with synaptagmin1 in SCG neurons, similar rat artery nerves. CaV2.3 and CaV2.1, like VNUT, localize to the periphery of the varicosities, while CaV2.2 more closely mimics to the distribution of VMAT2. These findings mirror our observations in rat tail artery, in which NE release is most sensitive to CaV2.2 inhibition and ATP‐mediated contraction is blocked by CaV2.3 inhibition. CONCLUSION We show that synaptic organization of CaV2 isoforms with specific pools of vesicle in a cultured nerve system closely recapitulates that found in vivo. This observation further validates cultured SCG neurons as an experimentally tractable and physiologically revenant model to study presynaptic cell biology relevant to the regulation of both cardiac output and vasoregulation. Support or Funding Information 1. Natural Sciences and Engineering Research Council of Canada.2. Canadian Foundation for Innovation