The novel thromboxane A2 receptor antagonist KW-3635 abolishes the cyclic flow reduction in the canine carotid artery

We tested the hypothesis that the abolition of the cyclic flow reduction (CFR) in the canine carotid artery is related to inhibition of ex vivo platelet aggregation following administration of KW-3635, a thromboxane A2 receptor antagonist, or aspirin. The CFR was induced in the carotid artery of anesthetized dogs by mechanical injury and narrowing of the artery. After induction of CFR, KW-3635 or aspirin was administered every 30 min at doses of 0,1,0.3, 1 and 3 mg/kg (i.v.). The ex vivo platelet aggregation, induced by sodium arachidonate and collagen, was also examined before and 15 min after each administration. KW-3635 and aspirin, at doses of 1 mg/kg i.v. and above, inhibited CFR and ex vivo platelet aggregation. These results that CFR in the canine carotid artery is platelet-dependent.

Protective effect of cisapride against indomethacin-induced obstruction of the gastric mucosal hemodynamics in rats

We investigated the effect of cisapride, a gastroprokinetic agent, on the obstructed gastric mucosal hemodynamics induced by indomethacin using an organ reflectance spectrophotometry system in rats. Indomethacin (10 mg/kg, i.v.) reduced both the gastric mucosal blood volume and the gastric mucosal blood oxygenation. Pretreatment with cisapride (0.1 mg/kg, i.v.) prevented these deteriorations. The presently-clarified gastric mucosal protective effect of cisapride may contribute to its therapeutic efficacy.

Protective effect of KW-3635, a specific thromboxane A2-receptor antagonist, on experimental glomerulonephritis in mice

We studied the effect of KW-3635, a selective thromboxane A2 (TXA2)-receptor antagonist, on experimental glomerulonephritis. The glomerulonephritis was induced in mice by the administration of rabbit anti-mouse glomerular basement membrane (GBM) antibody. It was characterized as proteinuria, changes of serum biochemical parameters and glomerular histopathological abnormalities. The administration of KW-3635 (30 mg/kg/day, p.o.) significantly ameliorated the proteinuria, elevation of serum urea nitrogen and the thickening of GBM. These data suggest that TXA2 may play an important pathogenic role in the development and progression of glomerulonephritis.

Antithrombotic effects of KW-3635, a thromboxane A2-receptor antagonist, in guinea pigs

Antithrombotic effects of KW-3635, a newly synthesized thromboxane (TX) A2-receptor antagonist, were studied in guinea pigs. In the extracorporeal circulation thrombosis model, the shunt was filled with thrombi, and reduction of platelet count and increase in plasma TXA2 concentration were observed. KW-3635 (30 and 100 mg/kg, p.o.) inhibited the thrombus formation in the shunt and prevented the decrease in platelet count in the circulating blood without affecting the red blood cell count. BM13,505 (30, 100 mg/kg, p.o.), another TXA2-receptor antagonist, and ticlopidine (300 mg/kg, p.o.), an antiplatelet drug, also inhibited the thrombus formation, while aspirin (10, 300 mg/kg, p.o.) did not. Peripheral arterial occlusive disease was induced by injection of sodium laurate into the femoral artery in guinea pigs. Daily oral administration of KW-3635 (3-30 mg/kg) significantly prevented the progression of vascular lesions. BM13,505 (3-30 mg/kg, p.o.) and ticlopidine (100 mg/kg, p.o.) also ameliorated the vascular lesions, whereas aspirin (10, 100 mg/kg, p.o.) did not. KW-3635 at concentrations up to 10(-4) M did not affect coagulation parameters in vitro. These results suggest that TXA2 is involved in the pathogenesis of arterial thrombotic and ischemic disorders. KW-3635 may be useful for the treatment of thrombotic disease and peripheral arterial occlusive diseases.

Enhancement by KW-5092, a novel gastroprokinetic agent, of the gastrointestinal motor activity in dogs

KW-5092 ([1-[2-[[[5-(piperidinomethyl)-2- furanyl]methyl]amino]ethyl]-2-imidazolidinylidene) propanedinitrile fumarate) is a novel gastroprokinetic agent with acetylcholinesterase (AChE) inhibitory activity and acetylcholine (ACh) release facilitatory activity. The present study examined the effects of KW-5092 on gastrointestinal (GI) motor activity in dogs. In anesthetized dogs, KW-5092 at 0.03 to 1 mg/kg, i.v. dose-dependently enhanced the gastric antral and the colonic motor activity. Neostigmine, an AChE inhibitor, enhanced the motor activity at 0.03 and 0.1 mg/kg, i.v. Ranitidine, a histamine H2-receptor antagonist with AChE inhibitory activity and ACh release facilitatory activity, enhanced the motor activity but decreased blood pressure at 1 to 10 mg/kg, i.v. In conscious dogs, KW-5092 at 0.03 to 1 mg/kg, i.v. or 1 to 10 mg/kg, p.o. dose-dependently enhanced the gastric antral, duodenal, ileal and the colonic motor activities. Neostigmine at 0.1 mg/kg, i.v. or 3 mg/kg, p.o. enhanced the duodenal, ileal and colonic motor activities, but induced excitement, slavering, vomiting and diarrhea. Ranitidine at 3 mg/kg, i.v. enhanced the gastric antral and colonic motor activities, but induced collapse or akinesia. The present results suggest that KW-5092 enhances the GI motor activity in a wide range from the gastric antrum to the colon and does not induce behavioral and cardiovascular side effects. KW-5092 may be a useful drug for the treatment of GI motility dysfunctions.

Protective effects of KW-3902, a novel adenosine A1-receptor antagonist, against gentamicin-induced acute renal failure in rats

We investigated the possible renal protective effects of KW-3902 (8-(noradamantan-3-yl)-1,3-dipropylxanthine), an adenosine A1-receptor antagonist, against gentamicin (GM)-induced acute renal failure (ARF) in rats. ARF was induced by subcutaneous injection of GM at 80 mg/kg/day for 12 days. KW-3902 (0.001-0.1 mg/kg, p.o., twice daily) attenuated the increases of serum creatinine and urea nitrogen and the decrease of creatinine clearance in rats treated with GM. In contrast, furosemide and trichlormethiazide aggravated the GM-induced nephrotoxicity. These results suggest that KW-3902 can ameliorate the GM-induced ARF and that endogenous adenosine may be involved in GM-induced ARF via the adenosine A1-receptor.

Protective effects of KW-3635, a thromboxane A2 antagonist, on arachidonic acid-induced transient cerebral ischemia in dogs

We investigated the effect of KW-3635, a selective thromboxane (TX) A2-receptor antagonist, on the arachidonic acid (AA)-induced transient cerebral ischemia in anesthetized dogs. Intracarotid-arterial injection of AA (0.25-1 mg/kg) produced a transient and reversible decrease in electroencephalographic (EEG) activity. The reduction of EEG power was inhibited by the intravenous injection of KW-3635 or aspirin, a cyclooxygenase inhibitor. Local cortical perfusion (LCP) measured by a laser-doppler flow meter was also reduced concomitantly with the reduction of EEG power. Although KW-3635 at 1 and 3 mg/kg (i.v.) did not affect the maximum reduction of LCP, the duration of the reduction period of LCP was significantly shortened by KW-3635. On the other hand, aspirin at 1 and 3 mg/kg (i.v.) inhibited both the maximum and the delay of LCP reduction. The intravenous administration of KW-3635 or aspirin caused dose-dependent inhibition of ex vivo platelet aggregation stimulated by AA (150 microM) at the doses that improve the EEG activity. These data suggest that TXA2 is one of the important factors in the AA-induced transient reduction of EEG activity in anesthetized dogs. The TXA2-receptor antagonist may be useful for protection against the ischemic brain damage following transient ischemic attack.

Anti-proliferative effects of benidipine hydrochloride in porcine cultured vascular smooth muscle cells and in rats subjected to balloon catheter-induced endothelial denudation

Using the [3H]thymidine incorporation technique, the anti-proliferative effects of benidipine, a long-acting calcium antagonist, on porcine cultured vascular smooth muscle cells (VSMCs) were determined and compared with those of other calcium antagonists. Benidipine inhibited serum-stimulated [3H]thymidine incorporation into VSMCs (IC50, 0.2 microM), and this inhibitory effect was significantly more potent than that of nitrendipine, felodipine, nisoldipine, manidipine, amlodipine, nifedipine, verapamil and diltiazem. When growth-arrested cells were stimulated with platelet-derived growth factor followed by insulin, benidipine, administered with either stimulation, inhibited [3H]thymidine incorporation into VSMCs. This suggests that it acts in both the G0/G1 and G1/S phases. In another series of experiments, the anti-proliferative effect in vivo was investigated using rats subjected to balloon catheter-induced endothelial denudation of the aorta. Benidipine (5 mg/kg, p.o., b.i.d.) significantly reduced the incorporation of [3H]thymidine into aortic DNA 48 h after balloon injury, whereas it did not affect incorporation into bone marrow, suggesting that it inhibits arterial DNA synthesis. From our results, benidipine was shown to exert antiproliferative effects on VSMCs in vivo as well as in vitro. The drug may be useful for the treatment of vascular proliferative diseases such as restenosis following percutaneous transluminal angioplasty and atherosclerosis.

Inhibitory action of benidipine on balloon catheterization-induced intimal thickening of the carotid artery in rats

We examined the effect of benidipine, a long lasting Ca2+ channel blocker, on balloon catheterization-induced intimal thickening of the carotid artery in rats. In the carotid arteries of vehicle-treated rats, neo-intima formation and elevation of DNA content was observed at 14 days after the surgery. Benidipine (5 mg/kg, p.o., b.i.d.) halved the intimal thickening and suppressed the elevated DNA-content in the balloon catheter-injured artery. These results suggest that benidipine may be useful for the treatment of vascular proliferative diseases like restenosis following percutaneous transluminal angioplasty.

Effects of KW-5092, a novel gastroprokinetic agent, on the delayed colonic propulsion in rats

The effects of KW-5092, [1-[2-[[[5-(piperidinomethyl)-2- furanyl]methyl]amino]ethyl]-2-imidazolidinylidene]propanedinitr ile fumarate, on the loperamide- or clonidine-induced delayed propulsion were determined in rats and compared with those of other gastroprokinetic agents. Administration of loperamide (0.3 mg/kg, s.c.) or clonidine (0.01 mg/kg, s.c.) induced delay of the evacuation time of the teflon ball, which had been inserted into the distal colon. The delayed evacuation was improved dose-dependently by KW-5092 at 3 to 10 mg/kg (p.o.) or higher. Neostigmine at 0.3 to 3 mg/kg (p.o.) and T-1815 at 1 to 100 mg/kg (p.o.) also improved the delayed ball evacuation. These results suggest that KW-5092 stimulates the delayed colonic propulsion.

Enhancement by KW-5092, a novel gastroprokinetic agent, of the release of acetylcholine from enteric neurons in the guinea pig ileum

KW-5092 ((1-[2-[[[5-(piperidinomethyl)-2-furanyl]methyl]amino]ethyl]-2- imidazolidinylidene) propanedinitrile fumarate) is a novel gastroprokinetic agent with acetylcholinesterase (AChE) inhibitory activity. The present study examined the effects of KW-5092 on intestinal contraction and on acetylcholine (ACh) release in the isolated longitudinal muscle-myenteric plexus preparation of guinea pig ileum. In the electrically stimulated preparation, KW-5092 enhanced the contraction at 10(-9) M to 3 x 10(-6) M and potentiated the ACh release at 10(-8) M to 3 x 10(-6) M. In the unstimulated preparation, KW-5092 at 10(-8) M to 10(-4) M evoked the contraction and ACh release. Both the contraction and the ACh release by KW-5092 were abolished by tetrodotoxin (10(-7) M) or removal of external Ca2+, and the evoked contraction was abolished by atropine (10(-7) M). The ACh release by KW-5092 was not affected by hexamethonium (3 x 10(-5) M), suggesting that the nicotinic receptor is not involved in the ACh release. Neostigmine, whose AChE inhibitory activity is equipotent to that of KW-5092, did not evoke ACh release even at 3 x 10(-6) M, indicating that the ACh release by KW-5092 is not due to its AChE inhibitory activity. The present results suggest that KW-5092 evokes ACh release by stimulating a cholinergic pathway and that the ACh release by KW-5092 may contribute to its gastroprokinetic effects.

Protective effects of benidipine against myocardial damage following ischemia and reperfusion in the isolated perfused rat heart

We investigated the possible protective effects of benidipine (Coniel), a calcium antagonist, on mechanical dysfunction, metabolic damage and changes in vascular reactivity during ischemia and reperfusion in the Langendorff-perfused rat heart. The responses of perfusion pressure to U-46619, a vasoconstrictor, and acetylcholine, an endothelial-dependent vasodilator, were also determined as indices of the vascular function. Thirty min of reperfusion following 30 min of global ischemia produced contractile failure and the marked release of lactate dehydrogenase (LDH) and creatine phosphokinase (CPK). Additionally, the ischemia and reperfusion augmented the vasoconstrictor response to U-46619, and depressed the endothelium-dependent vasodilator response to acetylcholine. These hearts were treated with 1 or 10 nM benidipine from 20 min before ischemia to the beginning of ischemia. While benidipine at 10 nM had a modest negative inotropic action, 1 nM of this drug had minimal depressant effects on the preischemic function. The depressed contractile function after the ischemia was improved, and the increased releases of LDH and CPK were significantly ameliorated by benidipine. Also, benidipine restored the augmented contractile response to U-46619 and preserved the vasodilator response to acetylcholine. These results demonstrate that pretreatment with benidipine prevents myocardial injury following ischemia and reperfusion. The cardioprotective effects of benidipine may in part be due to the protection of vascular reactivity by this drug.

Diuretic effects of KW-3902, a novel adenosine A1-receptor antagonist, in various models of acute renal failure in rats

Using various models of acute renal failure (ARF) in rats, the diuretic effects of 8-(noradamantan-3-yl)-1,3-dipropylxanthine (KW-3902), a novel adenosine A1-receptor antagonist (0.01 and 0.1 mg/kg, p.o.), were determined and compared with those of furosemide (30 mg/kg, p.o.) and trichlormethiazide (TCM; 1 mg/kg, p.o.). In cisplatin-induced ARF rats, KW-3902 and TCM, but not furosemide, increased Na excretion. KW-3902 did not affect creatinine clearance (CCRE), while TCM decreased CCRE. In gentamicin-induced ARF rats, KW-3902 increased urine volume (UV) and Na excretion. In glycerol-induced oliguric ARF rats, KW-3902, but not furosemide or TCM, increased UV, Na and K excretion and tended to improve the depressed CCRE, suggesting that the improvement of renal hemodynamics might also contribute to the diuretic effect of KW-3902. In glycerol-induced polyuric ARF rats, only KW-3902 significantly increased UV and Na excretion. These results demonstrate that KW-3902 induces natriuretic effects in various models of ARF and that the effect of KW-3902 is more prominent than those of furosemide and TCM. The present results suggest that endogenous adenosine may be involved in various forms of ARF via adenosine A1-receptors.

Effects of KW-3902, a novel adenosine A1-receptor antagonist, on cephaloridine-induced acute renal failure in rats

We investigated the possible renal protective effects of KW-3902 (8-(noradamantan-3-yl)-1,3-dipropylxanthine), a selective and potent adenosine A1-receptor antagonist, against cephaloridine (CER)-induced acute renal failure (ARF) in rats. ARF was induced by intravenous injection of CER at a dose of 600 mg/kg body weight. KW-3902 at doses higher than 0.01 mg/kg (p.o.) dose-dependently attenuated the decrease of creatinine clearance and the increase of proteinuria in rats with CER-induced ARF. In contrast, furosemide and trichlormethiazide (TCM) increased urinary protein and aggravated the serum parameters. These results suggest that KW-3902 has some advantages over furosemide and TCM when used in combination with CER. In the diuretic study in the rats with established ARF induced by CER, KW-3902, furosemide and TCM caused a significant increase in sodium excretion, whereas acetazolamide was ineffective. These results suggest that the proximal tubule is functionally damaged in rats with CER-induced ARF, in accord with the histological observation demonstrating the degeneration of the proximal tubule. From the fact that KW-3902 induces diuretic action even in CER-induced ARF, it is suggested that KW-3902 acts, directly or indirectly, on the proximal tubule or other tubular sites in the kidney, resulting in the diuretic effect.

Effects of KW-3635, a specific thromboxane A2-receptor antagonist, on the development of lupus nephritis in NZB x NZW F1 mice

We examined the effect of KW-3635, a specific thromboxane A2 (TXA2)-receptor antagonist, on the development of lupus nephritis in NZB x NZW F1 mice. KW-3635 was orally given once a day for 33 weeks beginning at eight weeks of age. In the control group, the mice began to die at 39 weeks of age, showing severe proteinuria and histopathologic abnormality in the renal glomeruli. Administration of KW-3635 (30 mg/kg/day) significantly reduced urinary protein excretion (1.7 +/- 0.9 vs. 8.5 +/- 2.4 mg/6 hr/mouse, P < 0.01), mortality (1/18 vs. 6/19, P < 0.05) and the histopathologic score of the kidney examined at 41 weeks of age. Thus, chronic administration of KW-3635 markedly attenuated the renal disease in NZB x NZW F1 mice, suggesting that TXA2 is an important mediator of the pathogenesis in this murine model of lupus nephritis.

Inhibitory effect of KW-3635, a new thromboxane A2-receptor antagonist, on arterial thrombosis in guinea pigs

The antithrombotic effects of the thromboxane (TX) A2-receptor antagonist and aspirin were determined using a photochemically-induced arterial thrombosis model in the femoral arteries of guinea pigs. KW-3635 (sodium (E)-11-[2-(5,6-dimethyl-1-benzimidazolyl)ethylidene]-6,11- dihydrodibenz[b,e]-oxepine-2-carboxylate monohydrate) and BM-13505, both of which are TXA2-receptor antagonists, and aspirin inhibited the thrombus formation at the doses that inhibited the ex vivo platelet aggregation induced by sodium arachidonate (100 microM) or collagen (3 micrograms/ml). These results support the notion that TXA2 is an important mediator in the present model of arterial thrombogenesis.

Colonic giant migrating contractions induced by glycerol enema in anesthetized rats

Colonic motility was measured with three catheter pressure transducers that were inserted into the descending colon at the distance of 4 cm, 6 cm and 8 cm from the anal verge in anesthetized rats. Colonic infusion of glycerol (65%, 2 ml/kg) induced large phasic pressure changes with high amplitude and long duration. Some of the pressure changes propagated over all the three recording sites, appearing to be equivalent to giant migrating contractions. These glycerol-induced large propulsions were abolished by lidocaine (5%, 2 ml/kg, intracolon), hexamethonium (10 mg/kg, i.v.) or clonidine (30 micrograms/kg, i.v.); and they were almost entirely suppressed by atropine (3 mg/kg, i.v.), suggesting the principal involvement of the cholinergic neural pathway.

Diuretic effects of KW-3902 (8-(noradamantan-3-yl)-1,3-dipropylxanthine), a novel adenosine A1 receptor antagonist, in conscious dogs

The diuretic effects of KW-3902 (8-(noradamantan-3-yl)-1,3-dipropylxanthine), a novel adenosine A1 receptor antagonist, were determined and compared with those of trichlormethiazide (TCM) and furosemide in saline-loaded conscious dogs. KW-3902, at doses higher than 0.1 mg/kg (p.o.), produced dose-dependent increases of urine volume and sodium excretion and these effects were statistically significant at doses of 1-100 mg/kg. The increase in potassium excretion was lower than that of sodium, and the ratio of sodium to potassium excretion (Na/K) tended to be elevated. TCM (0.3 mg/kg) and furosemide (3 mg/kg) also induced increases in urine volume and sodium excretion. The diuretic effects of KW-3902 lasted for 4 h after administration, whereas TCM and furosemide caused significant natriuresis for 2 h after administration. Thus, KW-3902 exhibited a longer lasting natriuresis than TCM and furosemide. These results indicate that adenosine A1 receptor blockade by KW-3902 causes consistent diuresis and natriuresis in dogs and suggest that adenosine A1 receptor blockade is a promising approach to diuretic therapy.

Effects of repeated administration of KW-3902, a novel adenosine A1-receptor antagonist, on its pharmacological actions

Effects of repeated administration of KW-3902, a novel adenosine A1-receptor antagonist, on its pharmacological actions were studied with regards to: 1) in vivo adenosine A1-antagonism, 2) diuretic effects and 3) renal protective effects against glycerol-induced acute renal failure (ARF). After repeated oral administration of KW-3902 (0.1 mg/kg/day) for 24 days, neither enhancement of the sensitivity to 5'-N-ethylcarboxamidoadenosine (NECA) nor reduction of the inhibitory effect of KW-3902 on the NECA-induced bradycardic response were observed. After repeated oral administration of KW-3902 (0.01 and 0.1 mg/kg/day) for 20 days, the diuretic effects of KW-3902 did not change. Renal protective effects against glycerol-induced ARF were not reduced by repeated oral administration of KW-3902 (0.01 and 0.1 mg/kg/day) for 23 days. These results suggest that repeated oral administration of KW-3902 has no effect on its pharmacological actions. Additionally, changes in serum parameters, which occurred after repeated administration of furosemide or trichlormethiazide, were minimal after repeated oral administration of KW-3902 (0.001-1 mg/kg/day) for 27 days. From these results, KW-3902 proved to be a diuretic which has renal protective effects with less side effects.

Pharmacological properties of KF18259, a novel 5-HT3-receptor antagonist, in rats: inhibition of the distal colonic function

We investigated the effects of KF18259 (endo-(8-methyl-8-aza- bicyclo[3.2.1]oct-3-yl)-1-isobutyl-2-oxo-1,2-dihydro-4-quinolinecarboxyl ate hydrochloride), a novel 5-HT3-receptor antagonist, in a variety of rat models, which are assumed to be mediated via 5-HT3 receptors, in comparison with those of YM060 ((R)-5-[(1-methyl-3-indolyl)carbonyl]-4,5,6,7-tetrahydro-1H- benzimidazole hydrochloride), granisetron and ondansetron. KF18259 inhibited wrap-restraint stress-induced defecation. The doses of KF18259 to inhibit wrap-restraint stress-induced defecation were lower than those to inhibit the 5-HT-induced von Bezold-Jarisch reflex and the cisplatin-induced slowing of gastric emptying. In contrast, the doses of YM060, granisetron and ondansetron to inhibit these three responses were similar. Moreover, KF18259 inhibited the wrap-restraint stress-induced propulsive motility of the proximal and distal colon. The effect of KF18259 on the distal colon was as potent as that on defecation and was more potent than that on the proximal colon. These results indicate that KF18259 potently inhibits the distal colonic function. KF18259 may be a useful tool for the discrimination of the 5-HT3-receptors located on the distal colon and other tissues.

Effects of adenosine A1-agonist and -antagonist on urinary volume and Na excretion in IAP-treated and non-treated rats

Effects of an adenosine A1-receptor agonist and antagonist were determined in pertussis toxin (IAP)-treated and non-treated rats. (-)-N6-(2-phenylisopropyl) adenosine, an adenosine A1-agonist, reduced the urine volume and sodium excretion without decreasing the glomerular filtration rate at 0.1 mg/kg (p.o.) in both IAP-treated and non-treated rats. Diuretic effects of KW-3902 (8-(noradamantan-3-yl)-1,3-dipropylxanthine) and 8-cyclopentyl-1,3-dipropylxanthine, adenosine A1-receptor antagonists, were not affected by pretreatment with IAP. These results suggest that endogenous adenosine may induce antidiuretic effects by accelerating the reabsorption of water and sodium at tubular sites via an IAP-insensitive mechanism, and that the diuretic effects of the adenosine A1-receptor antagonist may result from inhibiting this action of endogenous adenosine.

[MRI study of the brain in aged volunteers: T2 high signal intensity lesions and high cortical function]

In order to characterize age-related and chronological changes of the brain, longitudinal studies of aged volunteers were conducted using computed tomography since 1982. The present paper discusses correlations between brain function and findings of MR images which were obtained a using 1.5 T superconductive MR instrument since 1989. A total of 118 volunteers aged 60 to 88 years old with a mean age of 75.0 +/- 6.7 participated in the study, which consisted of MRI, EEG recording, the Benton Visual Retention Test and a medical interview. Subjects with a past history or clinical evidence of CVD, head trauma or dementia were excluded from the study. Incidence of T2 high signal intensity lesions increased with age. Some showing T1 low signal intensity in the same lesion were considered to be lacunar infarction, over all incidence of which was 24.6%. Numbers of correct responses on the BVRT showed a negative correlation with numbers of T2 high signal intensity lesions. Although the aged volunteers in the present study could achieve all activity of daily living without any trouble, high cortical function evaluated by visuoperceptual performance of BVRT was somewhat disturbed in participants with multiple T2 high signal intensity lesions. Brain atrophy seems to be more advanced in groups with T2 hyper intensity lesions than in the group without them. These findings may support the notion that T2 high signal intensity lesions are not merely an index of ageing but pathologic lesions accompanied with senescence, although further studies including clinicopathological correlation are necessary to establish this concept.

Inhibitory effects of KW-3902, a selective adenosine A1-receptor antagonist, on the adenosine-induced shortening of action potential duration in guinea pig atrial muscles

We investigated the effects of KW-3902 (8-(noradamantan-3-yl)-1,3- dipropylxanthine), a newly-synthesized selective adenosine A1-receptor antagonist, on the shortening of action potential duration (APD) in guinea pig atria exposed to adenosine. The APD shortening by adenosine was inhibited by KW-3902 at higher than 10(-8) M, but not by 10(-5) M of KF17837, an adenosine A2-receptor antagonist. These results support the notion that the APD shortening by adenosine in atria is mediated via adenosine A1-receptors. The potency of KW-3902 in antagonizing the APD-shortening were similar to those in antagonizing the negative inotropic and chronotropic action of adenosine in the isolated right atria, suggesting that these responses to adenosine are mediated via the receptors of the same type.

[Validity of clinical diagnosis in age-associated dementia]

With neuropathological diagnosis as the point of reference, the validity of clinical diagnosis was studied in 50 patients who had met DSM-III-R criteria for dementia. Clinical diagnosis of ATD (dementia of Alzheimer type) was made in 14 cases, of VD (vascular dementia) in 14 cases, of others in 5 cases and of undefined in 16 cases. At necropsy, 16 cases fulfilled the histological criteria for ATD, while 15 cases were VD, 3 cases were mixed dementia and 14 cases were other CNS disorders. In 2 other cases, the neuropathological picture was considered to be nondiagnostic. The accuracy of clinical diagnosis of VD was higher than that of ATD. Clinical diagnostic sensitivity was 81.8% for ATD and 91.7% for VD; corresponding specificity was 78.3% and 86.4%. With our clinical criteria, slowly evolving VD with no clinical evidence of stroke would not be identified as VD. On the other hand, AD patients who happened to have a stroke would be diagnosed as VD. These results suggest that further investigations as to VD (its clinical course, findings of computed tomographic scan and magnetic resonance imaging) are needed for more appropriate clinical criteria.

Diuretic and renal protective effects of 8-(noradamantan-3-yl)-1,3-dipropylxanthine (KW-3902), a novel adenosine A1-receptor antagonist, via pertussis toxin insensitive mechanism

KW-3902 [8-(noradamantan-3-yl)-1,3-dipropylxanthine] is a novel potent and selective adenosine A1-receptor antagonist. In anesthetized rats, KW-3902 (0.1 and 1 mg/kg p.o.) antagonized the 5'-N-ethylcarboxamidoadenosine (NECA) induced bradycardic response, which is thought to be mediated via adenosine A1-receptors. However, the hypotensive response to NECA, which is predominantly due to adenosine A2-receptor activation, was not affected by KW-3902. Diuretic and renal protective effects of KW-3902 were investigated in normal and pertussis toxin (IAP; 10 micrograms/kg i.v.)-treated rats. KW-3902 (0.001-1 mg/kg p.o.) caused significant increases of urine volume and sodium excretion with little change of potassium excretion in saline-loaded normal rats. In anesthetized normal rats, KW-3902 (0.01 and 0.1 mg/kg i.v.) caused significant diuresis and natriuresis with no change in renal plasma flow and glomerular filtration rate. These findings suggest that KW-3902 caused the diuretic effect not by the change in the renal hemodynamics, but by the inhibition of water and sodium reabsorption in tubular sites. KW-3902 (0.01-1 mg/kg p.o.) significantly attenuated increases of serum creatinine and urea nitrogen and renal tubular damage in glycerol-induced acute renal failure rats. Neither diuretic nor renal protective effects of KW-3902 were affected by pretreatment of rats with IAP, which totally abolished the bradycardic response to NECA. These results are compatible with the hypothesis that diuretic and renal protective effects by adenosine A1-receptor blockade are mediated via IAP-insensitive mechanism.