Role of cuneiform nucleus in regulation of sympathetic vasomotor tone in rats.

The cuneiform nucleus (CnF) is a sympathoexcitatory area involved in the central cardiovascular regulation. Its role in the maintaining vasomotor tone has, however, not yet been clarified. In the present study the effects of cobalt chloride (CoCl(2)) a nonselective synapse blocker and NMDA and non-NMDA glutamate receptors on resting mean arterial blood pressure and heart rate of CnF have been evaluated. CoCl(2), AP5 (an NMDA receptor antagonist) and CNQX (an AMPA/kinase receptor antagonist) (100nl) were microinjected into the CnF of anesthetized rats. The blood pressure and heart rate were recorded throughout the experiment. The responses of blood pressure and heart rate were compared with the pre-injection (paired t-test) and control (independent t-test) values. Microinjection of CoCl(2), AP5 and CNQX did not change the basal blood pressure and heart rate. In conclusion, our present study indicates that the CnF is not important in the regulation of cardiovascular tone.