Effect of papaverine on organic anion transport in rat kidney cortical slices

The present studies were conducted to further investigate a role of cyclic nucleotides for organic anion transport in rat kidney cortical slices by using papaverine as a phosphodiesterase inhibitor. Papaverine was chosen for this study because this drug is an organic cation, a transport system of which is thought to be clearly separable from an organic anion transport system. Papaverine inhibited not only p-aminohippuric acid (PAH) accumulation in the slices but also urate one. Pretreatment of the slices with papaverine was effective for significant inhibition of PAH accumulation during subsequent incubation in the absence of papaverine. The present results suggest that a relationship may exist between cyclic nucleotides and organic anion transport in rat kidney cortical slices, although further work is necessary before the above evaluation can be given.

Changes in the effects of clonidine on left atrium and hindlimb vasculature of rats in various thyroid states. A study of the responsiveness of alpha 2-adrenoceptors in the cardiovascular system

Postsynaptic alpha 2-adrenoceptors have been reported to exist in various tissues, including vascular smooth muscle. In order to investigate the possibility of their mediating a positive inotropic change and clarify the influence of the thyroid on their responsiveness, we examined the effects of clonidine, a known alpha 2-agonist, on the isolated left atria and femoral vascular beds of rats which were made hypo-, hyper- or euthyroid. Clonidine caused a dose-dependent positive inotropic change in the hypothyroid rat atrium, which was thought to be due to its alpha 1-stimulating action because of the antagonistic effect exerted by either phentolamine (10(-6) M) or prazosin (10(-7) M), but not by yohimbine (10(-7) M) or cimetidine (10(-5) M). In the hyperthyroid rat atrium, clonidine exerted a negative inotropic effect at high concentrations, which was thought to be due to its direct action on the cardiac muscle. Clonidine did not cause any inotropic change in the euthyroid rat atrium. Thus, an inotropic change mediated by the postsynaptic alpha 2-adrenoceptors could not be demonstrated in the rat heart. In the experiment involving hindlimb perfusion, clonidine caused vasoconstriction which was antagonized by yohimbine (10 micrograms/min). This effect was significantly augmented in the hypothyroid rats but not changed in the hyperthyroid ones. The vasoconstrictive effect of phenylephrine was found to be reduced in both hypo- and hyperthyroid rats. These results suggest that, in the peripheral vascular system, thyroid function also influences the postsynaptic alpha 2-adrenoceptors, but not in the same way as it affects the alpha 1-adrenoceptors.

Effects of biofeedback training on tonic masticatory neck reflex: a case report

Biofeedback training to reduce muscle tension lowered not only the spontaneous activity but also the tonic neck reflex in the jaw closing muscles. Tolperisone-HCl, which may inhibit the gamma system, inhibited the tonic masticatory neck reflex, but did not reduce the patient's spontaneous activity of the jaw closing muscles in this case. Biofeedback training may be considered to reduce the gamma as well as alpha motor systems.

Induction of opposite response of hindlimb vasculature to adrenergic agents in hypothyroid rats

In order to investigate whether hypothyroidism induces some functional change in the vascular smooth muscle, the responsiveness of the femoral vascular bed of hypothyroid rats to vasoactive agents was compared with that of euthyroid rats. The vascular beds were perfused by using the constant flow method. Ad libitum feeding of 0.15% 6-propylthiouracil to young male Wistar rats (120 g) over 3 months leads to hypothyroidism. Hypothyroidism did not induce any changes in the Ach- or papaverine-induced vasodilation and 5-HT-induced vasoconstriction. In contrast to euthyroidism, hypothyroidism induces a marked augmentation of the clonidine-induced vasoconstriction, while the phenylephrine-induced vasoconstriction and isoprenaline-induced vasodilation were clearly attenuated. The response to phenylephrine in euthyroidism was predominantly inhibited by prazosin and was slightly modified by yohimbine. While the attenuated response to phenylephrine in hypothyroidism was modified by these blockers in a converse manner, the response to clonidine in each rat group was not modified by prazosin, but markedly inhibited by yohimbine. From these results the following conclusions were obtained: both alpha-1 and alpha-2 adrenoceptors in the femoral vascular beds of eu- and hypothyroid rats responded to phenylephrine; phenylephrine stimulated predominantly alpha-1 adrenoceptors in euthyroidism; hypothyroidism caused an attenuation of the responsiveness mediated through alpha-1 adrenoceptors and an augmentation of that of alpha-2 receptors; hypothyroidism caused an opposite response, mediated through alpha- and beta-receptors, without influencing muscarinic and serotoninergic responses; augmentation of the alpha-2 response and attenuation of alpha-1 and beta-2 responses caused by hypothyroidism may be attributed to functional changes at receptor sites.

Hemodynamic effects of arotinolol in anesthetized dogs and its affinities for adrenoceptors in vitro

Hemodynamic actions of arotinolol in anesthetized dogs and its effects on alpha- and beta-adrenoceptors were examined. Arotinolol produced dose-dependent decrease in mean blood pressure, heart rate, cardiac output, maximum rate of left ventricular pressure rise and coronary blood flow in a dose range of 1 microgram/kg-3 mg/kg. Total peripheral resistance (TPR) increased with arotinolol dose-dependently in a dose range of 1 microgram/kg-0.3 mg/kg, but at doses of 1 and 3 mg/kg the increase in TPR was less. Arotinolol at a dose of 10 micrograms/kg significantly inhibited the blood pressure and heart rate responses to isoproterenol. Propranolol at the same dose produced only a slight inhibition of these. Arotinolol at a dose of 3 mg/kg attenuated the pressor response to phenylephrine without any effect on the response to angiotensin-II in anesthetized dogs. Propranolol at the same dose produced only a slight inhibition of the response to phenylephrine. In the study of radioactive ligand binding assays, arotinolol showed high affinities for both beta 1- and beta 2-adrenoceptors. Arotinolol showed an affinity also for alpha 1-adrenoceptors which was comparable to the affinity of yohimbine. Thus, the present results support the idea that arotinolol possesses both alpha- and beta-adrenoceptors blocking effects.

Phase I study of 2,4-diamino-6-(2,5-dichlorophenyl)-s-triazine maleate (MN-1695), a new anti-ulcer agent

A phase I study of 2,4-diamino-6-(2,5-dichlorophenyl)-s-triazine (MN-1695), which is expected to have an anti-ulcer effect, was performed in 14 healthy male subjects. The safety and pharmacokinetics were examined in single-dose oral administration of 1, 2, 4, 8 and 16 mg/body and multiple-dose administration of 2 mg/body/day, once daily, for 28 consecutive days. As for the subjective symptoms, only light headache, general malaise and heart burn were observed in two out of 4 subjects in the 16-mg group. No abnormalities were found in blood pressure, pulse rate, respiratory rate, body temperature, body weight and ECG both in single- and multiple-dose studies. No abnormal changes attributed to this drug appeared in hematological and biochemical examinations and urinalysis. Times for reaching the maximum plasma concentration in the single-dose study were 3.5, 8 and 3.3 h in 4-, 8- and 16-mg groups, respectively. The elimination half-lives from the plasma were 152, 145 and 148 h for the 3 groups, respectively. The plasma concentration curves in the multiple-dose study were similar to those simulated with the pharmacokinetic parameters obtained in the single-dose study. The plasma concentration increased until the 14th day, as the administration continued, and reached steady state thereafter; there seemed to be no abnormal cumulation. The elimination patterns after multiple-dose administration were almost the same as those in the single-dose study; the half-life was about 170 h.(ABSTRACT TRUNCATED AT 250 WORDS)

[Cefotiam passage into the maxillary sinus tissues]

Clinical study was made on cefotiam (CTM) and the following results were obtained. Tissue concentrations of CTM were determined 1 hour after intravenous injection (CTM 1 g) in chronic sinusitis and maxillary cyst. Concentrations of CTM were 16.53 micrograms/g, 13.26 micrograms/g in mucosa of the maxillary sinus, maxillary cyst, respectively. Antibacterial activity of CTM was measured on Escherichia coli, Staphylococcus epidermidis, Aerococcus, Acidaminococcus fermentans, Peptostreptococcus anaerobius; that were isolated from pus of maxillary sinus. The highest MIC on them was 3.13 micrograms/ml.

Effects of calcium antagonists on the electrical alternans of the ST segment and on associated mechanical alternans during acute coronary occlusion in dogs

Effects of calcium antagonists on the ST alternans and associated mechanical alternans during acute coronary occlusion were examined in anesthetized dogs. The heart rate was fixed by atrial pacing. The intravenous administration of 0.2 mg/kg verapamil attenuated the ST alternans as did 0.5 mg/kg diltiazem. Although these drugs significantly attenuated TQ depression during occlusion, the attenuation was observed after a longer period of occlusion and when the degree of TQ depression was comparable to that during the control occlusion. Nifedipine, 0.03 mg/kg, slightly attenuated the ST alternans, but 0.5 mg/kg dipyridamole had no effect. These results support the idea that slow inward currents are involved in the ST alternans. On the other hand, the mechanical alternans was attenuated in six of 11 dogs. It is probable that factors other than the electrical alternans may also contribute to the mechanical alternans.

Age-dependent differences in the positive inotropic effect of phenylephrine on rat isolated atria

The age-dependent differences in the involvement of alpha-adrenoceptors in the positive inotropic effect of phenylephrine (Phe) were examined in isolated atria of male Wistar rats 6 weeks (6W), 10 weeks and 7 months (7M) of age. The maximal increase in tension development induced by Phe increased with age, whereas the EC50 values for the positive inotropic effect of Phe did not change with age. The inhibitory effect of phentolamine on the response to Phe increased with age. Propranolol caused only slight inhibition of the effect of Phe in both 6W and 7M rats, and the EC50 values for Phe in the presence of propranolol did not change significantly with age. The EC50 values for isoprenaline and 5-hydroxytryptamine in 7M rats were higher than those in 6W rats. In 7M rats, the duration of the tension development was only slightly affected by Phe in the presence or absence of propranolol, but it was markedly decreased by Phe in the presence of phentolamine. The dose-response curve for Phe was markedly shifted to the left by papaverine in 6W rats, but slightly in 7M rats. The dose-response curve for isoprenaline was markedly shifted to the left by papaverine in both groups. These results are consistent with effects of Phe being mediated by both alpha- and beta-adrenoceptors in both 6W and 7M rats, but there is a shift in the balance from rather more beta-receptors in the young animals to more alpha-receptors in the adults.

Affinities for alpha- and beta-adrenoceptor subtypes of YM-09538, a new combined alpha- and beta-adrenoceptor antagonist, by radioligand binding assay

The binding properties of YM-09538 and some known adrenoceptor agonists and antagonists to alpha- and beta-adrenoceptors were studied by radioligand binding assays using [3H]-prazosin, [3H]-clonidine and (-)-[3H]-dihydroalprenolol ([3H]-DHA). The relative order of potencies of YM-09538 and 5 alpha-adrenergic agents for inhibition of [3H]-prazosin binding to rat brain membranes was as follows: prazosin greater than YM-09538 = phentolamine greater than labetalol greater than yohimbine greater than clonidine. In contrast, the order of potencies of these agents for [3H]-clonidine sites was as follows: clonidine greater than phentolamine greater than yohimbine greater than prazosin greater than YM-09538 greater than labetalol. The rank order of potencies of YM-09538 and 4 beta-adrenergic agents in inhibiting the binding of [3H]-DHA to guinea-pig heart membranes was the same as that to guinea-pig lung membranes: pindolol greater than propranolol greater than labetalol greater than YM-09538 greater than atenolol. Based on Ki values, YM-09538 displayed a 1,380-fold alpha 1-selectivity at alpha-adrenoceptors and no selectivity at beta-adrenoceptors. The biochemical potencies of YM-09538 observed in the present study correlated well with its pharmacological potencies obtained from previously reported literature.

Hen egg white ovomacroglobulin has a protease inhibitory activity

Hen egg white ovomacroglobulin purified by Miller and Feeney without reference to its activity was shown to have a protease inhibitory activity towards trypsin, papain, and thermolysin. It has four subunits of equal molecular weight (175,000 by SDS-PAGE) and each two of which are disulfide bonded. Upon incubation with trypsin it yields a fragment of Mr = 80,000 plus smaller ones. The subunit composition, amino acid composition and a newly found protease inhibitory activity place ovomacroglobulin as a closely related protein to human serum alpha 2-macroglobulin.

Effects of thymoxamine on ouabain-induced arrhythmias in dogs

The effect of thymoxamine, a pure alpha-adrenoceptor blocking agent, on ouabain-induced arrhythmias was investigated in dogs to clarify whether thymoxamine has an arrhythmogenic or an anti-arrhythmic action. Thymoxamine. 1 mg/kg i.v., inhibited the manifestation of ventricular arrhythmias (VA) and the pressor effect produced by ouabain infusion (1 microgram/kg/min i.v.) as 5 mg/kg i.v. of phentolamine did. Low doses of these drugs did not affect the VA. Simultaneous infusion of phenylephrine (5 micrograms/kg/min i.v.) with ouabain enhanced the manifestation of VA accompanying pressor effects, which were inhibited by thymoxamine (1 mg/kg) in a parallel manner. Infusion of isoprenaline (0.2 microgram/kg min i.v.) with ouabain enhanced the manifestation of VA, but the enhancement was to a lesser extent than with phenylephrine. Thymoxamine, 1 mg/kg, did not affect the VA. The infusion of CaCl2 (20 mg/kg/min i.v.) with ouabain enhanced the manifestation of VA, which was not inhibited by thymoxamine. These results show the possibility that the protective effect of thymoxamine on the manifestation of VA may be mainly associated with inhibitions of pressor effects mediated through vascular alpha-adrenoceptors.

Enhancement of avoidance-suppressing effect after repeated administration of haloperidol and serum haloperidol in rats

Adult male rats of the Wistar strain, which were trained under a discriminated lever-press avoidance schedule (intertrial interval; 25 sec. presentation of conditioned stimuli; 5 sec), were given SC 0.025-0.05 mg/kg of haloperidol at fixed intervals of 1, 3-4 and 7 days. The avoidance-suppressing effect of haloperidol was enhanced in parallel to the number of drug administrations until it attained a maximum level. The intensity of the maximum effect tended to be stronger, and the number of administrations necessary to attain it was smaller, when a higher dose was given. When the administration interval exceeded one day, the enhanced effect remained irreversible one month after withdrawal of drug administration. The enhancement of the effect was produced after repeated administrations in an experimental chamber, but not in a home cage. Temporal changes in serum haloperidol concentration were determined 30-90 min after 0.035 mg/kg given SC to the haloperidol-pretreated and saline-pretreated groups. No significant difference in the pharmacokinetic change was detected between the two groups. These results suggest that learning during the drug effect under repeated exposure to a fixed experimental situation influences the enhancing effect.

Influence of hypothyroid status on dopamine-induced positive chronotropic and inotropic effects on isolated rat atria

The involvement of alpha- and beta-adrenoceptors in dopamine (DA)-induced positive chronotropic and inotropic effects was investigated in isolated atria from euthyroid and hypothyroid rats. Propranolol at 3 x 10(-7) M remarkably inhibited the positive chronotropic effect of DA in both euthyroid and hypothyroid rats, and 1 x 10(-6) M phentolamine inhibited the effects of DA in the presence of propranolol in hypothyroid rats. Propranolol remarkably inhibited the positive inotropic effect of DA in both euthyroid and hypothyroid rats, while phentolamine was effective only in hypothyroid rats. In atria from reserpinized rats, the pD2-values for DA in both chronotropic and inotropic effects were reduced, but effectiveness of propranolol or phentolamine on DA-induced positive chronotropic and inotropic effects in euthyroid and hypothyroid rats was similar to that in non-reserpinized rats. In hypothyroid rats, DA increased the maximal rate of tension development, which was inhibited by both phentolamine and propranolol. DA shortened the duration of contraction. DA in the presence of phentolamine significantly shortened the duration of contraction but did not in the presence of propranolol. In conclusion the DA-induced positive chronotropic effect is mainly produced by beta-adrenoceptor stimulation in both euthyroid and hypothyroid rats, and also by a alpha-adrenoceptors to some extent in hypothyroid rats. The DA-induced positive inotropic effect is produced by alpha- as well as beta-adrenoceptor stimulation in both groups. However, alpha-adrenoceptors were involved to a greater extent in hypothyroid rats than in euthyroid rats. The stimulation of alpha-adrenoceptors by DA causes an increase in the maximal rate of tension development without a significant change in the duration of contraction, and the stimulation of beta-adrenoceptors by DA causes an increase in the maximal rate of tension development and shortening of the duration of contraction.

Pharmacological effects of several drugs on the myoepithelium and the vascular smooth muscle of the lactating mammary gland in goats

The present experiments were performed to investigate whether the responses of the myoepithelium to several drugs would be of a parallel nature with those of the vascular smooth muscle in the lactating mammary gland of goats. The drugs were injected into the mammary artery. Kallikrein, bradykinin, oxytocin, and acetylcholine caused marked milk-ejection with vasodilation in a dose-dependent manner. Marked milk-ejections with high doses of oxytocin were observed despite of accompanying vasoconstriction. The relative order of their potency in milk-ejection activity was kallikrein greater than bradykinin greater than oxytocin greater than acetylcholine: 1 greater than 1/100 greater than 3/1000 greater than 5/1000000. As for the vasodilator activity, the relative potency of the drugs was in the same order: 1 greater than 1/10 greater than 1/1000 greater than 1/10000. Catecholamines, histamine, serotonin, angiotensin-II, vasopressin and high doses of prostaglandin E2 caused dose-dependent vasoconstriction. Isoprenaline, pilocarpine, adenosine, PGI2 and low doses of PGE2 caused dose-dependent vasodilation. But these drugs did not affect milk-ejection. PGE1 decreased milk-ejection and was accompanied by vasodilation. From these experiments it is suggested that the relative order of the potency of secretagogues in milk-ejection activity and in vasodilator activity is nearly equal. It is also suggested that some drugs are different in their effects on the myoepithelium and on the vascular smooth muscle of the lactating mammary gland.

Association of stroke and myocardial infarction in children

A 9-year-old boy with cerebrovascular accident (CVA) and old myocardial infarction with mural thrombi is reported. The cause of the myocardial infarction was congenital coronary artery fistula originating from the left coronary artery and emptying into the right atrium. Although a common cause of strokes in adults, myocardial infarction has infrequently been reported as the source of emboli in children.