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Abstract:
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Thromboxane A2 (TXA2) is an arachidonic acid metabolite that is released during tissue trauma and elicits platelet aggregation and vascular smooth muscle contraction. Previous research has shown that TXA2 stimulates pulmonary and cardiac vagal afferent neurons. In addition, it has also been shown that TXA2 receptor (TP)mRNA is expressed in a sub-population of neurons in the nodose ganglia. This study was designed to further characterize the afferent vagal neurons that express TXA2 receptor gene transcript. We hypothesize that TP is expressed in nociceptive (pain-sensing) neurons. To test this, multiplex single-cell RT-PCR was employed on cultured nodose ganglion neurons from the rabbit. Primers for neurofilament medium (NFM), TP, and the capsaicin receptor (TRPV1) were added to the RT-PCR reaction. NFM was used as a positive neuronal marker, while the presence of TRPV1 was used to distinguish nociceptive from non-nociceptive neurons. Ninety-three cells were isolated from culture and RT-PCR was carried out on individual cells. Of the 79 NFM positive cells, 55 were TRPV1 positive and 20 were TP positive. Of the 20 TP positive cells, 13 (65%) were TRPV1 positive. Therefore, we conclude that the presence of TP mRNA in a subset of nociceptive neurons allows for the possibility that TXA2 may contribute to the onset of pain or activation of reflexes during myocardial ischemia by stimulating or modulating vagal afferent neurons. |
