XXXX sympathetic neurons express varying proportions of two distinct P2X receptors.

@entity7430 @entity840 @entity22751 @entity861 @entity35 @entity22752 @entity855
1. Characterization of P2X receptors on neurons of @entity840 superior cervical ganglion (SCG) has been carried out using a whole-cell voltage-clamp technique. 2. Application of @entity855 and @entity861 ( @entity861 ) produced fast activating inward currents, which desensitized slowly. The maximum response to @entity861 was 36 +/- 23 % (range 0.1-100 %) of that evoked by @entity855 in the same cell. 3. Co-application of @entity861 (300 microM) with @entity855 (300 microM) produced a response that was 97 +/- 1 % of that given by @entity855 alone. Following desensitization with @entity861 , the decrease in response to @entity855 was equal to the absolute reduction in response to @entity861 in the same cell. 4. The concentration-response curve for @entity861 had an EC50 of 42 microM and a Hill coefficient of 1.17. For cells where the ratio of @entity861 / @entity855 currents at 100 microM was < 0.1, the @entity855 concentration-response curve had an EC50 of 56 microM and a Hill coefficient of 1.95. However, in cells where the ratio was > 0.7, the curve had an EC50 of 60 microM and a Hill coefficient of 0.97. 5. The response to 100 microM @entity861 was inhibited by 2' (or 3')-O-trinitrophenyl- @entity855 ( @entity7430 - @entity855 ) with an IC50 of 70 nM. However, on cells where the ratio of @entity861 / @entity855 currents was < 0.1, @entity855 was inhibited by TNP- @entity855 with an IC50 of 522 nM. 6. Immunohistochemical staining with antibodies raised against @entity35 @entity22751 and @entity22752 epitopes suggested that both subunits were expressed by @entity840 SCG neurons. 7. We conclude that varying proportions of two distinct P2X receptors coexist on the cell bodies of individual @entity840 SCG neurons, which may correspond to homomeric @entity22751 and heteromeric @entity22751 /3 receptors.
