Time dependent effects of histamine on parameters of capillary transport of protein in canine hindquarters.

Although the effects of histamine to increase water and macromolecular transport are known to be transient, the methods previously utilized to assess solvent drag reflection coefficient (sigma) and permeability-surface area product (PS) usually require periods of observation longer than the length of the transients. Utilizing a method developed and analyzed in this laboratory (18-20), this study utilized the information from opposite changes in lumbar trunk lymph flow (L) and lymph to plasma protein concentration ratios (R) to compute sigma and PS over 10-minute intervals during histamine infusion at 0.5-1.5 mg base/kg/min into the abdominal aorta of the anesthetized dog. There was a highly reproducible decline in sigma from 46 to 56% during the first 50 minutes of infusion followed by a rise to 46% above control at 166 minutes. PS showed no time dependent variability and was widely variable independent of sigma. These studies indicate that histamine in the intact anesthetized canine hindquarters produces augmented vascular leakage of protein only for about 100 minutes, and that this augmented flux which is coupled to water flux occurs because of increased convective and not permeative or diffusive flux.