EVIDENCE FOR DIRECT INTERACTION OF KETAMINE WITH α- AND β2-ADRENOCEPTORS

1. Ketamine has a number of effects that suggest that it may interact with α- and β-adrenoceptors. To date, the experimental evidence for this has been indirect and has been based on physiological studies using competitive blocking agents. In the present study we sought to determine from receptor binding studies whether ketamine binds directly to α- and β-adrenoceptors. 2. Membrane preparations o. α₁- and β₂-adrenergic binding sites were obtained from urinary bladder and urethrae of sheep. These binding sites were characterized by saturation analyses using [³H]-prazosin for α₁-adrenoceptor binding sites and [¹²⁵I]-cyanopindolol (CYP) for the β₂-adrenoceptor binding sites. The receptors were further characterized by displacement studies using selective and non-selective antagonists. 3. Studies in which ketamine was used to displac. [³H]-prazosin revealed a K_d of 3.40±1.23× 10^?3 mol/L for ketamine binding to ai-adrenoceptors. Displacement studies of [¹²⁵I]-CYP by ketamine showed a K_d of 0.35±0.03× 10^?3 mol/L for ketamine binding to β₂-adrenoceptors. 4. We conclude that ketamine interacts directly with both ai- an. β₂-adrenoceptors and that such interactions probably explain the reported effects of this agent on the vasculature and the bronchial tree.     

The advantages of delayed imaging and radiographic correlation in scintigraphic localization of gastrointestinal bleeding

Two cases in which gastrointestinal bleeding was localized by serial scintigraphic imaging with red blood cells labeled in vivo with 99mTc-PYP are reported. The importance of both early serial imaging and delayed imaging and of the correlation with other radiographic techniques is demonstrated. Reflux of blood from the sigmoid into the proximal colon was observed in both cases. In one case, contrast material injected into a resected specimen confirmed the scintigraphic localization of the site of bleeding.     

Sanatorium admissions in a boys'' boarding school

A survey of sanatorium admissions in a boys' boarding school covering 11 “school years” from 1971 to 1982 is presented. Nine-nundred-and-seventy boys accounted for 1500 admissions. The average length of admission was 3·8 days. Classification of the three main groups-infections (57%), injuries (32%) and miscellaneous (11%) are given. The factors causing boys to be illness- and injury-prone are discussed. The value of a school sanatorium is stressed. The views of the boy patients are given.