The in vitro pharmacological profile of KR31080, a nonpeptide AT1 receptor antagonist

Summary— KR31080 (2-butyl-5-methyl-6-(1-oxopyridin-2-yl)-3-[[2'-(1H-tetrazol-5-yl) biphenyl-4-yl]methyl]-3H-imidazo[4,5-b] pyridine) is a potent inhibitor of angiotensin type 1 (AT₁) receptors in rabbit aorta and human recombinant AT₁ receptors. In the isolated rabbit thoracic aorta, KR31080 caused a nonparallel shift to the right of the concentration-response curves to angiotensin II (All) with decreased maximal response (pD'₂ = 10.1 ± 0.1), but had no effect on the contractile response induced by norepinephrine. KR31080 inhibited specific [¹²⁵I]AII binding to rabbit aortic membranes (AT, receptors) and [¹²⁵I][Sar¹, Ile⁸]AII binding to human recombinant AT₁ receptors in a concentration-dependent manner with IC₅₀ values of 0.84 ± 0.08 nM and 1.92 ± 0.15 nM, respectively, but did not inhibit specific [¹²⁵I)AII binding to bovine cerebellum membranes (ÀT₂ receptors). In the Scatchard analysis, KR31080 interacted with rabbit aortic AT₁ receptors in a competitive manner, similar to losartan. These results demonstrate that KR31080 is a potent and AT₁ selective angiotensin receptor antagonist which exerts a competitive antagonism in the [¹²⁵I]AII binding assay and insurmountable AT₁ receptor antagonism in the functional study.     

Respiratory symptoms and bronchial reactivity: identification of a syndrome and its relation to asthma

Two postal questionnaire surveys were carried out among the adult population of Southampton aimed at clarifying the diagnostic criteria for asthma (study 1) and at testing the validity of symptoms so identified as diagnostic of bronchial hyper-reactivity (study 2). The questionnaires asked about respiratory symptoms and included three questions thought likely to disclose increased bronchial reactivity. Laboratory measurements on subsamples of respondents included spirometry and bronchial challenge with increasing doses of histamine till a concentration was reached provoking a fall of more than 20% (PC greater than 20) in forced expiratory volume in one second. In the first study no normal subject (that is, one who did not report shortness of breath or wheezing on the questionnaire) had a PC greater than 20 below 0.5 g/l. Of 51 subjects who reported shortness of breath or wheezing, or both, nine had a cluster of abnormalities consisting of one or more symptoms of bronchial irritability, nocturnal dyspnoea, and prolonged morning tightness together with PC greater than 20 values of 0.5 g/l or less. These symptoms in conjunction with a low PC greater than 20 were termed the bronchial irritability syndrome. In the second study bronchial challenge confirmed the close association of these symptoms with bronchial hyper-reactivity, all other subjects being less reactive to histamine. Only 27% of subjects with symptoms of the bronchial irritability syndrome had been diagnosed as asthmatic by their general practitioners. The bronchial irritability syndrome is a definable entity for epidemiological study and patient care.     

Anterior cervical epidural abscess: the use of intraoperative spinal sonography

A case of acute cervical epidural abscess is presented. The use of intraoperative spinal sonography is discussed as a valuable adjunct in the evaluation and treatment of these uncommon lesions.     

Corpus callosum: interactive effects of infantile handling and testosterone in the rat

Previous research found that the corpus callosum of male rats is larger than that of females; handling rats in infancy enhances this sex difference; and female rat pups, when handled in infancy and given 1 injection of testosterone propionate (TP) on Day 4 of life, will have callosa as large as those of males. In 2 experiments, male pups were castrated on Day 1 or received sham surgery; female pups were injected with TP on Day 4 or received an oil injection. Litters were handled or nonhandled. The previous finding that females, when handled and given TP in infancy, have a larger callosum was confirmed; however, a TP effect when administered to nonhandled females was not found. Because handling is known to cause a corticosterone release, these findings were interpreted as evidence of a developmental interaction between adrenal and gonadal hormones at the cortical level.