EFFECT OF SYMPATHOMIMETIC AMINES ON THE HISTAMINE FORMING CAPACITY OF HUMAN LEUCOCYTES

Abstract

1 The effects of α- and β-adrenoceptor stimulants on the histamine-forming capacity (HFC) of human isolated leucocytes have been studied, in vitro. 2 It was confirmed that antigen significantly stimulates the HFC of human leucocytes. 3 β-Adrenoceptor stimulants, such as isoprenaline and salbutamol (10⁻⁶-10⁻³ m) significantly inhibited the HFC of human leucocytes in the presence and absence of antigen. At concentrations lower than 10⁻⁶ m, this effect was not observed. In general the degree of inhibition of HFC by β-adrenoceptor stimulants followed their potency as β-adrenoceptor stimulants. 4 α-Adrenoceptor stimulants significantly stimulated leucocyte HFC; noradrenaline within a limited concentration of 10⁻⁶ m, while stimulation was seen consistently with phenylephrine at concentrations of 10⁻⁷-10⁻⁴ m. Adrenaline, which stimulates both α- and β-adrenoceptors, produced small inhibition, no effect, or a degree of stimulation. 5 Phentolamine, an α-adrenoceptor blocking agent, produced an effect opposite to that of the α-adrenoceptor stimulants, i.e. a significant inhibition of the HFC of human isolated leucocytes.