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.     

Obesity and beta-blockers: influence of body fat on their kinetics and cardiovascular effects

Beta-blockers are among the most widely used antihypertensive drugs. They differ from each other in regard to several factors such as: beta-agonist activity, beta 1-selectivity and solubility. Aim of this work was to evaluate the influence of obesity on the kinetics and the antihypertensive effect of two Beta-blockers with different solubility such as: the water-soluble, atenolol and the liposoluble, metoprolol. The study was carried out according to an open randomized cross-over design. Eight obese hypertensive patients, after a two week washout period, were randomly allocated to a four week treatment. After a two week intermediate washout period, each patient switched to the other treatment for an additional four week period. On the first and the last day of each treatment the subjects were hospitalized to collect blood samples for the assay of the two drugs and to measure cardiovascular parameters. Obesity does not exert any effect on the kinetics of the water-soluble beta-blocker, atenolol, while markedly interferes with that of the liposoluble, without any apparent influence on its anti-hypertensive effect. These findings extend to obese hypertensives the concept that the plasma concentrations of beta-blocking agents are not reliable predictors of their therapeutic effect.     

A Chinese adolescent girl with Fechtner-like syndrome

We describe a 15-y-old girl with Fechtner-like syndrome, who is the first Chinese reported to have this rare syndrome. She presented with left homonymous hemianopia and neuroimaging revealed haemorrhage in both parietal and occipital lobes. Peripheral blood smear showed macrothrombocytopenia and intracytoplasmic inclusion bodies inside leucocytes. Thrombocytopenia and proteinuria responded to intravenous immunoglobulin and pulsed methylprednisolone. This case illustrates that life-threatening haemorrhage can occur in patients with Fechtner syndrome. Although there was no effective treatment reported in the literature, high dose steroid and immunoglobulin seemed to be useful in our patient. Our patient also had nephritic-nephrotic syndrome with renal insufficiency, which is unusual in adolescent female patients.     

Immunomodulatory effects of two extracts of Panax ginseng C.A. Meyer

The effect of Panax ginseng extracts on cell-mediated immune functions in man has been investigated. Three groups, each consisting of twenty healthy volunteers, were treated under conditions of double blindness with capsules containing lactose (Control Group B), with capsules containing 100 mg of aqueous extract of the drug (Group A), and with capsules containing 100 mg of standardized extract of the drug (Group C). All the patients took one capsule every 12 h for 8 weeks. Blood samples were withdrawn before beginning the treatment, at the fourth week and at the eighth week. The immune parameters examined were the following: chemotaxis of PMNs, phagocytosis index (PHI), phagocytosis fraction (PHF), intracellular killing, total lymphocytes (T3), T helper (T4) subset, suppressor cells (T8) subset, blastogenesis of circulating lymphocytes, natural killer-cell activity (NK). Chemotaxis proved to be enhanced (p less than 0.05) already at the fourth week in Group A as well as in Group C; the increase became even more marked (p less than 0.001) at the eight week in subjects belonging to Group C. PHI and PHF proved to be enhanced (p less than 0.05) at the eighth week in subjects of Group A; these increases were found to be higher in subjects of Group C (p less than 0.001) already starting at the fourth week. Intracellular killing was shown to be significantly increased (p less than 0.05) already at the fourth week in Groups A and C; the increase becomes highly significant in both groups (p less than 0.001) at the eighth week; however, a significant increase (p less than 0.05) at the eighth week was also noticed in the placebo group (Group B).(ABSTRACT TRUNCATED AT 250 WORDS)