Keizo Ito

Selective effect of KB-2796, a new calcium entry blocker, on cerebral circulation : a comparative study of the effects of calcium entry blockers on cerebral and peripheral arterial blood flows

The effects of a new calcium entry blocker, KB-2796, on cerebral and peripheral circulation were compared with those of four other calcium entry blockers (flunarizine, cinnarizine, nicardipine, and diltiazem) and also papaverine in anesthetized dogs. KB-2796 increased the vertebral blood flow to the same extent as the other drugs. KB-2796 and the other drugs increased the coronary blood flow, although the effect of KB-2796 was obviously weaker than that of the other drugs. The dose of KB-2796 producing a 30% increase in coronary blood flow was about 20 times higher than that producing an equivalent increase in vertebral blood flow. KB-2796 and the other calcium entry blockers caused a moderate increase in both femoral and common carotid blood flow. The renal artery showed a biphasic response to all drugs, which consisted of an initial decrease and a subsequent increase in the flow. From these results, it is suggested that KB-2796 is a new type of calcium entry blocker that selectively affects the cerebral circulation. It is also concluded that calcium entry blockers have a different spectrum of vasodilatory action on coronary and cerebral vascular beds and that a selective coronary vasodilatory action is not a common feature among all calcium entry blockers.

Inhibition of Chemical Mediator Release from Human Leukocytes and Lung in Vitro by A Novel Antiallergic Agent, Kb-2413

The effect of KB-2413 on IgE-mediated histamine and LTC4 release from leukocytes obtained from asthmatic patients who were sensitive to mites, and from human lung tissues passively sensitized with IgE myeloma serum was studied. KB-2413 inhibited the IgE-mediated chemical mediator release concentration dependently at a range of 10(-4) to 3 x 10(-3) M. KB-2413 did not enhance histamine release at a higher concentration unlike ketotifen. These findings suggest that the inhibitory effect of KB-2413 on the release of chemical mediators contributes to the anti-allergic activity of this compound.

Effects of a new diphenylpiperazine calcium antagonist, KB-2796, on cerebral ischemic neuronal damage in rats

1. The effects of KB-2796, a new diphenylpiperazine calcium antagonist, on the mitochondrial dysfunction and energy metabolism deficits were examined in the ischemic rat brain. 2. KB-2796 (30 mg/kg, p.o.), administered 60 min prior to decapitation, improved the reduced respiratory activity of mitochondria obtained from rat brain 5 min after decapitative ischemia. 3. KB-2796 (30 mg/kg, p.o.), administered 60 min prior to ischemic insult, improved both the reductions in pyruvate and ATP and prevented increases in the lactate/pyruvate ratio induced by 30-min forebrain ischemia in rats with 4-vessel occlusion (4-VO). 4. The effect of KB-2796 on local cerebral glucose utilization (LCGU) was examined by a quantitative autoradiographic 2-[14C]deoxyglucose method in normal and 4-VO rats. 5. Postischemic LCGU measured 24 hr after reperfusion in the forebrain, in particular in the cortex, thalamus, geniculate body, hippocampus, caudate-putamen, nucleus accumbens, colliculus, and corpus callosum, was below the normal control value. 6. KB-2796 (1 mg/kg, i.v.), administered 1 min prior to the injection of 2-[14C]deoxyglucose, improved the reductions in LCGU that were produced by cerebral ischemia in the cortex, thalamus, geniculate body, caudate-putamen, nucleus accumbens and substantia nigra, but did not affect LCGU in normal rats. 7. These findings suggest that KB-2796 minimized the deficits in brain energy metabolism produced by ischemia; this agent may therefore be a valuable therapeutic drug in cerebrovascular-related disorders.

Benzylpiperazine compound and pharmaceutical composition as hypolipidemic agent

Novel benzylpiperazine compound of the formula: ##STR1## or a pharmaceutically acceptable acid addition salt thereof, which has excellent hypolipidemic activity without undesirable side effect, and a pharmaceutical composition containing the compound as an active ingredient suitable for the prophylaxis and treatment of hyperlipidemia.

[Biochemical studies of acebutolol-the beta1 specificity of acebutolol (author's transl)].

Effects of acebutolol on carbohydrate and lipid metabolism in rats and on adenylate cyclase of heart and liver in dogs were investigated to determine the beta receptor blocking properties of the compound. Acebutolol exhibited the beta blocking activity and inhibited the increase of serum lactate concentration induced by adrenaline. This inhibition was about one-sixth as potent as that of propranolol. In hyperglycemic and free fatty acid effects of adrenaline, acebutolol inhibited the adrenaline-induced free fatty acid increase more effectively than hyperglycemia induced by adrenaline. In the inhibition of stimulated adenylate cyclase activity in the heart and liver, acebutolol was more active on the heart than on liver. Relative beta1 specificity of acebutolol was 93.2. Inhibition of propranolol on adenylate cyclase activity was more potent than that of acebutolol on both tissues, but showed no specificity. These results suggest that acebutolol is beta1 selective, although its beta blocking potency is less than that of propranolol.