Alpha 1-adrenoceptor antagonist activity of novel pyrimidine derivatives (SHI437 and IK29) in rabbit aorta and trigone of the bladder

Adrenoceptors in the Lower Urinary Tract

Adrenoceptors importantly contribute to the physiological regulation of lower urinary tract (LUT) function and have become a target of several clinically successful treatments for major LUT diseases. In the bladder dome, β-adrenoceptor subtypes are found in multiple cell types and mediate relaxation of detrusor smooth muscle, perhaps partly indirectly by acting on afferent nerves and cells of the mucosa. β₃-adrenoceptor agonists such as mirabegron and vibegron are used to treat overactive bladder syndrome. In the bladder trigone and urethra, α₁-adrenoceptors cause contraction and thereby physiologically contribute to bladder outlet resistance. α₁-adrenoceptors in the prostate also cause contraction and pathophysiologically elevate bladder outlet resistance leading to voiding dysfunction in benign prostatic hyperplasia. α₁-adrenoceptor antagonist such as tamsulosin is widely used as a first-line option to treat LUT symptoms in men, but it remains unclear to which extent and how smooth muscle relaxation contributes to symptom relief.

Toll-like receptor-4 modulates survival by induction of left ventricular remodeling after myocardial infarction in mice

Left ventricular (LV) remodeling is known to contribute to morbidity and mortality after myocardial infarction (MI). Because LV remodeling is strongly associated with an inflammatory response, we investigated whether or not TLR-4 influences LV remodeling and survival in a mice model of MI. Six days after MI induction, TLR4 knockout (KO)-MI mice showed improved LV function 32 and reduced LV remodeling as indexed by reduced levels of atrial natriuretic factor and total collagen as well as by a reduced heart weight to body weight ratio when compared with WT-MI mice. This was associated with a reduction of protein levels of the intracellular TLR4 adapter protein MyD88 and enhanced protein expression of the anti-hypertrophic JNK in KO-MI mice when compared with wild-type (WT)-MI mice. In contrast, protein activation of the pro-hypertrophic kinases protein kinase Cdelta and p42/44 were not regulated in KO-MI mice when compared with WT-MI mice. Improved LV function, reduced cardiac remodeling, and suppressed intracellular TLR4 signaling in KO-MI mice were associated with significantly improved survival compared with WT-MI mice (62 vs 23%; p < 0.0001). TLR4 deficiency led to improved survival after MI mediated by attenuated left ventricular remodeling.

N-arylpiperazinyl-N'-propylamino derivatives of heteroaryl amides as functional uroselective alpha 1-adrenoceptor antagonists

Novel arylpiperazines were identified as alpha 1-adrenoceptor (AR) subtype-selective antagonists by functional in vitro screening. 3-[4-(ortho-Substituted phenyl)piperazin-1-yl]propylamines were derivatized with N,N-dimethyl anthranilamides, nicotinamides, as well as carboxamides of quinoline, 1,8-naphthyridine, pyrazolo[3,4-b]pyridine, isoxazolo[3,4-b]pyridine, imidazo[4,5-b]pyridine, and pyrazolo[1,5-a]pyrimidines. Strips of rabbit bladder neck were employed as a predictive assay for antagonism in the human lower tract. Rings of rat aorta were used as a "negative screen" for the test antagonists. Binding to alpha 1-ARs was relatively sensitive to size and electronic features of the arylpiperazine portion of the antagonists and permissive to these features on the heteroaryl carboxamide side. These structure-affinity findings were exploited to produce nicotinamides (e.g. 13ii and 25x) and pyrazolo[3,4-b]pyridines (e.g. 37f and 37y) ligands with nanomolar affinity at the alpha 1-AR subtype prevalent in the human lower urinary tract(pA2 values: 8.8, 10.7, 9.3, and 9.9, respectively) and displaying 2-3 orders of magnitude selectivity over the alpha 1D-AR.

Prevention of intimal thickening after endothelial removal by a nonpeptide angiotensin II receptor antagonist, losartan

1. The present experiments were designed to investigate the role of local angiotensin II receptors in the myointimal proliferative response of the vascular wall after endothelial removal, by use of a novel, nonpeptide, angiotensin II receptor antagonist, losartan. 2. When administered 1 week before endothelial removal from the rabbit carotid artery and then continuously until animals were killed 6 weeks later, losartan in a dose of 10 mg kg-1 daily, p.o. had no significant effects on the carotid blood flow (CBF), mean arterial blood pressure (MBP) and heart rate (HR). 3. A full endothelial lining with increased density of regenerated endothelial cells was observed 6 weeks after the endothelial removal. These changes were unaffected by treatment with losartan. 4. Six weeks after endothelial removal, acetylcholine (ACh)- and adenosine diphosphate (ADP)-induced relaxations were greatly reduced though endothelial cells had regenerated. The reduction of the relaxations to these agonists were significantly restored by chronic treatment with losartan. The endothelial-independent, sodium nitroprusside (SNP)-induced relaxation remained unaffected in all groups. 5. There were no differences in the noradrenaline (NA)- and endothelin-1 (ET-1)-induced contractions of the carotid artery strips between vehicle and losartan-treated groups. In contrast, the contractile response of the strips to angiotensin II was significantly decreased in the losartan group, indicating the specific antagonism by chronic losartan against the angiotensin II receptor. 6. Six weeks after endothelial removal, marked myointimal proliferation resulting from new accumulation of proliferating smooth muscle cells and connective tissue was observed in the vehicle group. Losartan treatment greatly suppressed the myointimal proliferative response.7. These results suggest that the local angiotensin II receptors play a role in the myointimal proliferativeresponse of the vascular wall to removal of the endothelium.