Effect of intravenous versus intraperitoneal glucose injection on systemic hemodynamics and blood flow rate in normal and tumor tissues in rats.

The effect of i.v. versus i.p. glucose injections on blood flow rate of Walker 256 carcinoma and several normal tissues of unanesthetized, unrestrained female Sprague-Dawley rats was measured, using the radioactive microsphere technique prior to and 60 min after glucose administration (6 g/kg, i.v. or i.p.). Changes in systemic hemodynamics were also investigated in an attempt to further quantify the mechanisms responsible for tumor blood flow reduction. Most of the normal tissues showed either no modification or a decrease in the blood flow rate following i.v. or i.p. glucose injections. The response was more pronounced following i.p. injection. Most of the tissues studied also exhibited significant modification in cardiac output distribution. A decrease in blood flow rate and cardiac output distribution was also observed in the tumors following i.v. or i.p. injections. However, as observed in the normal tissues, the response was more pronounced following i.p. injection. Mechanisms for blood flow reduction include systemic effects such as reduction and redistribution of cardiac output. An additional systemic mechanism following i.p. injection includes hypovolemic hemoconcentration which was evident by an increase in blood hematocrit. In rats, unlike observations in mice, the change in hematocrit following i.p. injection is not as large and cannot account for the total blood flow reduction. Local mechanisms include an increase in red blood cell rigidity due to glucose itself and tissue acidosis.