The role of histamine and noradrenaline in allergic and exercise induced asthma of childhood, and the effect of theophylline treatment

Age-dependency of alpha- and beta-adrenoceptors on thrombocytes and lymphocytes of asthmatic and nonasthmatic children

Among the possible mechanisms which may cause wheezing or asthmatic episodes a genetically determined beta-adrenoceptor blockade and a hyperresponsiveness of alpha-adrenoceptors has been postulated. Evidence to support this hypothesis stems from an increased bronchial sensitivity to beta-blockers, a reduced formation of cyclic AMP in response to beta-adrenergic stimulation and enhanced alpha-adrenergic responses in asthmatic subjects. The recent development of techniques for measuring the specific, high-affinity binding of radiolabeled alpha- and beta-adrenergic antagonists made it possible to study alpha- and beta-adrenoceptors in vitro. Based upon the assumption that a change in the number and/or affinity of adrenergic receptors might be a general phenomenon, we have performed alpha- and beta-receptor binding studies on lymphocytes and platelets from wheezing infants and asthmatic children as well as of infants, children, and adults not suffering from these diseases. Using 125[I]-cyanopindolol (ICYP) and 3[H]-yohimbine (HYOH) as highly specific ligands for alpha- and beta-adrenoceptors, the following results were obtained: Lymphocytes and platelets from control subjects and asthmatics bound similar amounts of ICYP and HYOH and thus showed no differences either in the number or the affinity of alpha- and beta-adrenoceptors. Lymphocytes and platelets of wheezing and nonwheezing infants also bound the same amounts of the radioligands. In asthmatic children receiving 4 X 2 puffs salbutamol beta-adrenoceptors were down-regulated and this may mimic beta-adrenoceptor blockade. When subjects were divided into four categories according to age (0-5, 5-10, 10-20 years, adults) the number of beta-adrenoceptor binding sites showed an age-dependent increase.(ABSTRACT TRUNCATED AT 250 WORDS)

Measurement of plasma histamine by stable isotope dilution gas chromatography-mass spectrometry: methodology and normal values

A new method for the determination of histamine by stable isotope dilution mass fragmentography is described. The method is specific, sensitive, and accurate, resulting in a within-day coefficient of variation of 4.1% and a day-to-day variation of 7.9%. It was shown that the first blood sample after a venipuncture can contain an artificially elevated plasma histamine concentration. Platelets contain about 7 pmol histamine/10(9) cells. Serum histamine was elevated about four times in comparison with plasma histamine. This phenomenon was mainly ascribed to degranulation of basophilic leukocytes by complement activation during blood clotting. Normal values for plasma histamine were (n = 25) 2.07 +/- 0.75 nmol/liter (mean +/- 1 SD), which is one of the lowest values reported up to now.