Microinjection of a substance P analogue (1 mM; 7 or 10 nl) into laminae I and II of the L7 dorsal horn of decerebrate cats significantly potentiated (P < 0.05) the increase in arterial pressure evoked by microinjection of L- glutamate (109 mM; 7 or 10 nl) into these spinal sites. Microinjection of the substance P analogues (i.e., GR73638 and [Sar9, Met(O2)11] -substance P) which were selective NK-1 receptor agonists, had no impact on the cardioacceleration evoked by microinjection of L-glutamate (P > 0.05). In addition, microinjection of these analogues had no effect on the modest and non-significant increase in phrenic nerve discharge evoked by L-glutamate. We conclude that stimulation of NK-I receptors in the superficial laminae of the dorsal horn potentiates the pressor responses to microinjection of L- glutamate.
All Science Journal Classification (ASJC) codes
- Molecular Biology
- Clinical Neurology
- Developmental Biology