Is myocardial hyporesponsiveness to catecholamines in human sepsis associated with impaired beta-adrenergic receptor stimulation of cyclic adenosine monophosphate?
Septic shock is associated with impaired beta-adrenergic receptor stimulation of cAMP, which may contribute to myocardial hyporesponsiveness to catecholamines.
OBJECTIVES: To determine whether myocardial hyporesponsiveness to administered catecholamines occurs in human sepsis and whether this phenomenon is associated with impaired beta-adrenergic receptor stimulation of cyclic adenosine monophosphate. DESIGN: Prospective study. SETTING: Medical ICU in a university hospital. PATIENTS: Normal human volunteers (n = 7), critically ill patients who were not septic (n = 9), septic patients not in shock (n = 16), and septic patients in shock (n = 17). MEASUREMENTS AND MAIN RESULTS: Pulmonary artery catheter-derived hemodynamic data were obtained in patients with sepsis and septic shock. Isoproterenol and sodium fluoride-stimulated cyclic adenosine monophosphate accumulations were measured in circulating lymphocytes. The hemodynamic response to sequential infusions of dobutamine, 5 and 10 micrograms/kg/min, was obtained in septic and septic shock patients. Baseline hemodynamic values for mean arterial pressure, cardiac index, left ventricular stroke work index, and oxygen delivery index at approximately 2 days after the onset of sepsis were significantly lower in septic shock patients compared with septic (nonshock) patients (p < .01 p < .05, p < .001, p < .01, respectively). Isoproterenol- and sodium fluoride-stimulated cyclic adenosine monophosphate accumulations were significantly reduced in septic shock patients compared with those accumulations observed in septic patients (p < .01 and p < .001, respectively). The heart rate response to 10 micrograms/kg/min of dobutamine was significantly (p < .01) lower in septic shock patients compared with septic patients. CONCLUSIONS: In patients with septic shock, impaired beta-adrenergic receptor stimulation of cyclic adenosine monophosphate is associated with myocardial hyporesponsiveness to catecholamines, suggesting that beta-adrenergic receptor dysfunction may contribute to the reduced myocardial performance observed in this shock state.
Silverman et al. (Fri,) studied this question.