Cold Stress Provokes Sympathoinhibitory Presyncope in Healthy Subjects and Hemodialysis Patients With Low Cardiac Output

摘要: Background Sudden hypotension in progressive hypovolemia or during hemodialysis is attributed to sudden inhibition of sympathetic activity. Critical ventricular underfilling seems responsible for this paradox, but it unknown why the transition from sympathoactivation accompanying sympathoinhibition so abrupt. We studied whether brief fluctuation activity induced by cold pressor test (CPT) evokes if applied low cardiac output. Methods and Results Fourteen healthy subjects underwent CPT, lower-body negative pressure (LBNP; −45 mm Hg 60 minutes), combination thereof. CPT alone caused vasoconstriction increased muscle nerve activity, followed uneventful relaxation. When reduced output, tachycardia, prior LBNP 6 minutes, again vasoconstriction, now acute 10 subjects, was associated with vasorelaxation, relative bradycard...