Effects of Ringer-acetate and Ringer-dextran solutions on the microcirculation after LPS challenge: observations in the hamster cheek pouch.

The effects of NaCl 0.9%, Ringer-acetate, and Ringer-dextran given as intravenous infusions in the microcirculatory changes observed in early stages of endotoxemia were investigated in male hamsters treated with Escherichia coli lipopolysaccharide (LPS). The cheek pouch was studied in vivo by means of intravital microscopy. Mean arterial (MAP) and venous pressures (CVP), heart rate, mean arteriolar internal diameter, spontaneous arteriolar vasomotion (AV), red blood cell velocity (RBCV) in these vessels, and long-term effects of LPS were evaluated in animals treated with either LPS alone or the combination of LPS with NaCl 0.9%, Ringer-acetate and Ringer-dextran. The intravenous injection of LPS (0.3 mg/kg) elicited a significant reduction in MAP and CVP, cessation of AV and a decrease in RBCV. In our study, the heart rate and the arteriolar diameter did not change significantly, compared with the control values obtained before the LPS injection. No improvement in the MAP could be detected with infusions of NaCl 0.9% or Ringer-acetate but the infusion of Ringer-dextran increased it significantly. All infusions tested maintained the CVP until the end of the observation period and the Ringer-dextran increased it significantly. The heart rate was maintained around 360 beats/min with a tendency to decrease 70 min after the LPS infusion in all groups studied except the group which received NaCl 0.9% where the heart rate decreased significantly. In all the four groups, the mean arteriolar diameter did not change significantly with time during the observed period. RBCV decrease with the combination LPS + NaCl 0.9% and the infusions of Ringer-acetate and Ringer-dextran maintained it until the end of the observation period. The combination of LPS + NaCl 0.9% maintained the spontaneous arteriolar vasomotion during 50 min after LPS injection and the infusion of Ringer-acetate maintained it for the 3-h observation period. The infusion of Ringer-dextran maintained the amplitude of the spontaneous arteriolar vasomotion and increased its frequency significantly. The long-term effects of LPS showed weight loss and pus on the periorbital area. Our results suggest that the best solution to maintain the microcirculatory parameters during the early stage of endotoxemia after LPS injection was the Ringer-dextran.