Pulmonary Extraction of N-Isopropyl-I-123-p-Iodoamphetamine in the Presence of Propanolol Using Dual Indicator Dilution Technique

Abstract

DOI: http://dx.doi.org/10.5915/18-1-11734

In order to determine the sensitivity of the procedure for detecting and measuring pharmacological intervention in the pulmonary endothelial amine receptors, propranolol was administered intravenously to the intact dogs at different dose levels. Pulmonary extraction of N-Isopropyl-I-123-p-lodoamphetamine (IMP) with and without pharmacological intervention was determined by the rapid sequential imaging, following the intravenous injection of a reference tracer and later a test tracer. Input vascular and organ time-activity curves were obtained. The input vascular ond organ curves oj the reference tracer were gamma fitted and were deconvolved. Predicted residue function for the test tracer was determined by convolving the inpuf vascular curve of the test tracer with the impulse response function of rhe reference tracer under stable physiological conditions. The calculated first pass pulmonary extraction values of IMP in the pretreated dogs with propranolol given ten minutes prior to the reference tracer in the dose of 1, 3, 5, 10, /5 and 20mg were 0.81. 0.77. 0.71, 0.62, 0.62, and 0.62, respectively, relative to Tc-99m dextran as a reference tracer, whereas the normal IMP first pass pulmonary extraction was 0.90 ± 0.03. Uptake of IMP may provide a sensitive probe with which to detect and evaluate the physiological interaction of pulmonary endothelial cell in a clinical environment using a noninvasive procedure.