The Neural Function of Cuneiform Nucleus in Non- Hypovolemic and Hypovolemic Hypotensive Rats: Single Unit Recording

Hemorrhagic hypotension results from a life-threatening loss of blood and physiologically decreases baroreceptor discharge and leads tochemoreceptor stimulation, due to stagnant anoxia induced by decreased blood flow to the chemoreceptors. Cuneiform nucleus (CnF) located in center of circuit that mediated autonomic responses related to stress. In this study, the CnF neurons activity in hypotensioninduced by hemorrhage and hydralazine, as an antihypertension drug, evaluated by blood pressure and single unit recording. Materials and Methods: Animals groups were: Control, Hemorrhage and Hydralazine. After anesthesia, femoral artery and tail vein of rats were cannulated for recording cardiovascular responses include in Systolic blood pressure (SBP), Mean arterial pressure (MAP) and heart rate (HR) and drug injection. Also, single unit recording performed from CnF neurons. Results: The results showed that in Hydralazine groups, maximal change (Δ) of SBP and MAP significantly decreased and HR significantly increased than Control group. Also, in Hemorrhage group, ΔSBP and ΔMAPsignificantly decreased and ΔHR significantly increased than Control group. After the hypotension induction or hydralazine injection relatively significant increase in spike frequency as well as PSTH showed. Conclusion: Current study has been shown that CnF has a cellularfunction in the hypovovemic and non-hypovolemic hypotension in the rats. Probably mechanisms are relationship between CnF and other vasomotor nuclei and then existence of volume sensitive receptors that response to the hypovolemic hypotension.