The peripheral platelet count in response to intravenous infusion of isoprenaline

5 healthy male volunteers received i.v. infusions of isoprenaline in doses of 0.03, 0.06 and 0.09 mug X kg-1 X min-1 over a period of 6 min. A statistically significant decrease in the peripheral platelet count was obtained, but no dose-response-curve for isoprenaline was observed. It is suggested that while an i.v. infusion of epinephrine causes a release of platelets from the exchangeable splenic platelet pool, isoprenaline might have the opposite effect on the spleen, thereby causing a decrease of platelets in the peripheral blood.