Comparison of capsaicin-evoked calcium transients between rat nodose and jugular ganglion neurons.
The objectives of this study were to describe the size distribution of capsaicin-sensitive neurons in nodose and jugular ganglia and to determine whether there is a difference in capsaicin sensitivity between these two types of ganglia. Functional identification was made by measurement of the capsaicin-evoked calcium (Ca2+) transients in cultured vagal sensory neurons of young adult Sprague-Dawley rats using the Fura-2-based ratiometric imaging technique. In the first study series, cells on the second day of culture were perfused with capsaicin solution (10(-7) M) for 15 s, and the Ca2+ transients were continuously recorded before, during, and after the capsaicin challenge. Out of 603 viable neurons, 57.5% were capsaicin-sensitive; the percentages of capsaicin-sensitive cells in the nodose and jugular ganglia were 59.8% and 55.4%, respectively. Capsaicin sensitivity predominated in the small- and medium-sized neurons; the capsaicin-sensitive cells generally had a diameter less than 35 microm in both types of ganglia. Although the results did not indicate any differences in the size distribution of capsaicin-sensitive neurons between the two ganglia, results of our second study series showed that a near-maximal concentration of capsaicin (3 x 10(-6) M) evoked a significantly greater peak Ca2+ transient in jugular neurons (382.5 +/- 85.5 nM) than in nodose neurons (134.3 +/- 17.5 nM). In summary, our results showed that an increase in cell diameter was accompanied by a decreasing trend in percentage of capsaicin-sensitive neurons in both vagal ganglia. Capsaicin at high concentration evoked a greater peak Ca2+ transient in jugular ganglion neurons, despite no difference in the responses to KCl between these two types of ganglion neurons.
Chung
Eleanor
E
Department of Physiology, University of Kentucky Medical Center, Lexington 40536-0298, USA.
Gu
Qihai
Q
Kwong
Kevin
K
Arden
Warwick A
WA
Lee
Lu-Yuan
LY
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002211:Capsaicin / Q000031:analogs & derivatives* / Q000494:pharmacology*; D002452:Cell Count; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D005924:Glomus Jugulare / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D009620:Nodose Ganglion / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley
C071423:capsazepine; D002211:Capsaicin; D002118:Calcium