title: Central impairment of renal nerve response to stimulation of medullary pressor area in rabbit endotoxic hypotension.
abstract: The present study was designed to determine if there is a central abnormality in the sympathetic efferent outflow through the brainstem in endotoxic hypotension. Mean blood pressure (MBP), heart rate (HR) and renal nerve activity (NA) were recorded simultaneously following intravenous injection of endotoxin (1 mg/kg). MBP fell significantly so that 30 min and 60 min after the injection, MBP were 76 +/- 11 mm Hg and 56 +/- 10 mm Hg respectively. Simultaneously with decreases in MBP, NA and HR also decreased significantly. Peak responses in MBP and NA to repetitive stimulation of medullary pressor area (MPA) were attenuated significantly after endotoxin. Onset and peak latencies of renal nerve discharges (RNDe) evoked by the electrical stimulation of the MPA at 5 min after endotoxin were significantly shorter than that before endotoxin, followed by a recovery to the pre-endotoxin level. Peak and total activities of RNDe were reduced significantly so that 30 min after endotoxin activities were 53 +/- 9% and 53 +/- 11% of pre-endotoxin levels respectively. However, responses in MBP, NA and RNDe to the stimulation of the thoracic sympathetic chain did not differ significantly between before and after injection of endotoxin. These data confirm the presence of a central neural abnormality in central sympathetic outflow in the hypotension induced by E. coli endotoxin.
mesh_terms: D000818:Animals; D001794:Blood Pressure; D004558:Electric Stimulation; D004926:Escherichia coli; D006339:Heart Rate; D007022:Hypotension / Q000503:physiopathology*; D007668:Kidney / Q000294:innervation*; D008297:Male; D008526:Medulla Oblongata / Q000503:physiopathology*; D011817:Rabbits; D012772:Shock, Septic / Q000503:physiopathology*; D013564:Sympathetic Nervous System / Q000503:physiopathology; D014666:Vasomotor System / Q000503:physiopathology*