Measurement of rate of extravasation of plasma protein in inflammatory responses in guinea-pig skin using a continuous recording method.

The technique described consists of monitoring the extravasation of intravenously injected 125I-labelled plasma albumin in a fold of skin during a response to an inflammatory stimulus. A system was devised for the measurement of intravascular clearance of labelled albumin; and the equation to the clearance curve was used to compute corrections to the data obtained in skin monitoring experiments. Concentration of intravascular labelled protein was determined by taking a blood sample after each experiment, counting it in a well counter and using the clearance curve to calculate the blood concentration immediately following intravenous injection. This enabled results to be expressed in terms of extravasation of plasma in μl/min. Little change in skin intravascular volume was observed in inflammatory responses, as measured by 32P-red blood cell count. Basic differences were observed between responses elicited by a range of agents, illustrated by a comparison between: histamine; prostaglandin E1; kallikrein; thermal injury; and lymphokine. The technique is compared with other methods.