Failure of buffered 5-hydroxytryptamine to increase brain capillary permeability to albumin in monkeys

✓ The effect of buffered 5-hydroxytryptamine (5-HT) on the blood-brain barrier to 125I-albumin was studied in 14 rhesus monkeys. Buffered 5-HT was introduced into the lateral ventricle by ventriculocisternal perfusion, resulting in a concentration gradient in the periventricular tissue from 1 to 800 times endogenous levels. Buffered 5-HT failed to induce an increase in periventricular vascular permeability to 125I-albumin. The author suggests that previous contrary reports from other laboratories may have resulted from species differences and failure to control certain physiological parameters including the use of highly acidic 5-HT preparations.