Uptake of 3,4-dimethoxyphenylethylamine-1-14C (14C-DMPEA) by rat tissues in vitro.

Rat heart and spleen slices were incubated with 3,4-dimethoxyphenylethylamine-1-14C(14C-DMPEA) in Krebs medium at 37 C. At the end of 5-20 min of incubation, the heart did not take up the radioactivity while the spleen did. The Km and Vmax values of uptake in the spleen were 1 x 10(-4) M and 20 nmole/g per min, respectively, and the uptake was reduced to 16.0-35.1% in the cold (4 C) and to 40.3-64.0% in Na+-free medium. Thus, the uptake was an energy-dependent active process but was only partially Na+-dependent. Spleen slices incubated with 14C-DMPEA-free medium for 15 min following incubation with 14C-DMPEA retained 41.0-74.8% of radioactivity. The uptake was insensitive to norepinephrine (0.313 and 0.939 muM), dopamine (9.98 muM), 5-hydroxytryptamine (5 muM), cocaine (14.8 muM), 1-amphetamine (0.3 and 300 muM), d-amphetamine (300 muM), and normetanephrine (45.7 muM). 6-Hydroxydopamine treatment of rats, which produced 93% reduction in the splenic norepinephrine content, did not significantly reduce uptake. Thus, the uptake of DMPEA into the spleen is not by adrenergic neurones.

Some observations on the development of adrenergic innervation in rabbit intestine.

1 Stimulation of periarterial nerves to the ileum of 1 to 12 day old rabbits with supramaximal voltages and frequencies of 1, 2, 5, 10 and 20 Hz with square wave pulses of 2--5 ms duration for 30--40 s produced responses that were initially contractor. In the course of the first week, the responses changed from motor to inhibitory, the change occurring first at the highest rates of stimulation. By the 7th day of life, almost all responses were inhibitory. 2 The motor responses were potentiated by physostigmine and blocked by hyoscine suggesting that they were mediated by acetylcholine. 3 In preparations from rabbits older than 3 days, motor responses could be converted to inhibitory ones by prior exposure to noradrenaline (NA, 1 microgram/ml) for 20 min. This procedure also significantly increased the responses which were already inhibitory. 4 The ability of the ileum to take up NA increased with age. This uptake was blocked by cocaine. 5 The following explanations are possible: (a) changeover from cholinergic to adrenergic transmission in sympathetic fibres; (b) existence of 'parasympathetic' splanchnic nerves or a permanent cholinergic 'sympathetic' component of splanchnic nerves and (c) temporal delay in the development of adrenergic nerves (compared with cholinergic nerves) in the intestine.

Effect of tyramine on human umbilical artery in vitro.

Fifteen of twenty-one perfused human umbilical artery preparations constricted in response to tyramine. These responses were unaffected by atropine, mepyramine or bromolysergic acid diethylamide but were blocked by phentolamine or dihydroergotamine. Cocaine augmented the constriction responses to tyramine or noradrenaline but not those to adrenaline, acetylcholine or 5-hydroxytryptamine. Infusion of noradrenaline restored the responses of preparations which had become tachyphylactic to tyramine.

Factors affecting the action of guanethidine on adrenergic neurones.

1. The uptake of guanethidine by adrenergic neurones has been studied indirectly by testing the ability of various procedures to prevent or reverse adrenergic neurone blockade in the periarterially stimulated isolated ileum preparation.2. Adrenergic neurone blockade was prevented but not reversed by equilibration with guanethidine (3.3 x 10(-6)M) at low temperatures (10 degrees C), in the absence of sodium or in the presence of tetrodotoxin (0.3 x 10(-6)M) or noradrenaline (1.2 x 10(-3)M).3. Calcium (5 x 10(-2)M) both prevented and, to some extent, reversed the adrenergic neurone blocking action of guanethidine.4. Equilibration with guanethidine in the presence of mersalyl (0.6 x 10(-7)M) or in the absence of potassium or calcium could neither prevent nor reverse adrenergic neurone blockade.

Effects of various drugs on insulin antibodies.

1. Insulin antibodies were induced in young guinea-pigs of both sexes weighing 300-400 g and housed in a room maintained at 28 degrees C+/-2 degrees C, by subcutaneous injection of 2 ml of freshly prepared insulin antigen emulsion between the shoulders once every month.2. To estimate the titre of serum antibody the serum was incubated with a known concentration of insulin for 90 min at 37 degrees C and the insulin not bound to antibody was estimated by the rat hemidiaphragm method.3. No significant (P>0.5) development of insulin antibody could be detected in the serum samples collected 1 month after the first and 15 days after the second monthly injections in groups of ten male guinea-pigs and six female guinea-pigs. However, the titre of insulin antibody in the serum of these groups of guinea-pigs 15 days after the third monthly injection of insulin antigen emulsion was significantly (P<0.01) raised. There was no further increase in the titre of insulin antibody in the sera 15 days after the fourth and fifth monthly injections of insulin antigen emulsion. Thus the peak titre was reached 15 days after the third monthly injection of the antigen.4. Two groups of ten male guinea-pigs each received testosterone propionate or diethylstilboestrol daily for 1 week after each monthly injection of insulin antigen emulsion. Two other groups of six female guinea-pigs each received testosterone propionate or diethylstilboestrol in a similar manner. One more group of ten female guinea-pigs received both sex hormones for 1 week after each monthly injection of insulin antigen emulsion. Testosterone facilitated the induction of insulin antibody in the serum of males but did not affect the antibody titre in the female guinea-pigs. Diethylstilboestrol facilitated the induction of insulin antibody in the serum of groups of either sex, the peak titre being attained after the second monthly injection of insulin antigen emulsion. The response of the females which received both sex hormones was similar to that of females which received diethylstilboestrol alone.5. Fifteen days after the third monthly injection of insulin antigen emulsion a group of ten guinea-pigs received hydrocortisone subcutaneously each day for 1 month. The serum antibody titre was estimated at the end of the drug treatment, and was significantly (P<0.01) reduced.6. Fifteen days after the third monthly injection of insulin antigen emulsion three different groups of five-six guinea-pigs each received tolbutamide, chlorpropamide or phenformin orally every day for a month. Antibody titres of the serum were estimated at the end of this period; there was no significant (P>0.05) reduction in groups receiving chlorpropamide or phenformin, but the serum antibody titre of the group receiving tolbutamide was significantly (P<0.01) raised.7. Fifteen days after the third monthly injection of insulin antigen emulsion different groups of five-six guinea-pigs received one of the following: 5-bromouracil, 5-fluorouracil, 6-mercaptopurine, methotrexate, 6-azauridine, busulphan, chlorambucil, cyclophosphamide, actinomycin-D or mytomycin-C intraperitoneally each day for 5 days. The serum antibody titre of all the groups of guinea-pigs was significantly (P<0.01) reduced. On the other hand the serum antibody titre of a control group of six guinea-pigs receiving normal saline intraperitoneally each day for 5 days was not significantly (P>0.5) affected.

The role of the sympathetic nervous system in oestrogen-induced hypertension in rats.

Albino rats of either sex received chronic ethinyl oestradiol (EO) treatment (1.5 mg kg-1 daily, i.m.) for 3 weeks. Untreated control rats received arachis oil vehicle alone. Chronic EO treatment resulted in elevation of blood pressure in both sexes. Female rats exhibited significantly greater elevation in blood pressure than males. In chronic EO-treated rats pressor responses to low doses (0.5 micrograms kg-1) of noradrenaline were significantly increased, while those to angiotensin II, acetylcholine and isoprenaline were unaltered. Chronic EO treatment also sensitized the vascular bed of the rats' hindquarters to noradrenaline. EO-induced hypertension was associated with significant increase in dopamine-beta-hydroxylase activity of adrenal glands. Complete bilateral adrenalectomy or chemical sympathectomy prevented the development of EO-induced hypertension. It is suggested that chronic treatment of rats with EO induces and maintains hypertension. The peripheral sympathetic system plays an important role in this phenomenon.

Effect on body temperature in dogs of perfusion of cerebral ventricles with artificiaL CSF deficient in calcium or containing excess of sodium or calcium.

In anaesthetized dogs at room temperatures of 28-33 degrees C, the cerebral ventricles were perfused with artificial CSF from the left lateral ventricular to the aqueductal cannulae. The animals' temperatures were recorded from the rectum. Addition of Ca(++) in excess to the artificial CSF perfusing the ventricles produced hyperthermia and addition of Na+ in excess produced hypothermia. Perfusion with medium deficient in Ca(++) and containing sodium edetate produced hypothermia. The temperature effects of Na(+) or Ca(++) in excess were mutually antagonistic.

Kinetics and some characteristics of uptake of noradrenaline by the human umbilical artery.

The uptake of exogenously added noradrenaline (NA) (0.5-2.5 mug/ml) by the human umbilical artery was linear with time up to 10 minutes. The uptake was saturable and could be described by the Michaelis-Menten equation. The uptake was cocaine-resistant, normetanephrine-sensitive, was considerably inhibited in the cold and was partially inhibited by Na+- deficiency. Of NA accumulated in the artery 31% could be washed out by NA-free medium. It is concluded that the mechanism of uptake of NA by the human umbilical artery is similar to the uptake2 mechanism.

Some characteristics of the adrenergic neurone blocking action of dehydroemetine.

The uptake of dehydroemetine by adrenergic neurones was studied indirectly by testing the ability of various procedures to prevent or reverse adrenergic neurone blockade in the periarterially stimulated rabbit isolated ileum. Adrenergic neurone blockade was prevented but not reversed by equilibration with dehydroemetine at low temperature (0 degrees C), in the absence of sodium or in the presence of tetrodotoxin. Noradrenaline, cocaine, potassium deprivation and potassium excess did not modify the adrenergic neurone blocking action of dehydroemetine.

Analysis of the effects on body temperature of intracerebroventricular injection in anaesthetized dogs of gamma-aminobutyric acid.

1 The cerebral ventricles of dogs under intravenous pentobarbitone sodium anaesthesia, were perfused with artificial cerebro-spinal fluid (CSF) at a rate of 0.4-0.5 ml/min from the ventricular to the aqueductal cannulae. The effluent was collected from the aqueductal cannula in 20 min samples. The animals' temperatures were recorded from the rectum.2 gamma-Aminobutyric acid (GABA) 0.1-5 mg when injected into the ventricles produced variable temperature effects. Doses of 0.1 and 0.5 mg always produced hyperthermia and 1 and 5 mg doses sometimes produced hyperthermia and sometimes hypothermia.3 Intraventricular perfusion with 2-bromolysergic acid diethylamide (BOL) and hyoscine did not block hyperthermia. Tests on the rat isolated stomach strip or the guinea-pig isolated superfused ileum for the possible release, respectively, of 5-hydroxytryptamine or acetylcholine by GABA were negative.4 When tested for the presence of prostaglandin E(PGE)-like substances on the isolated rat stomach strip, both the control effluent and the GABA effluent showed activity, the latter being much more potent. There was a temporal correlation between this effect and hyperthermia. Intraventricularly administered sodium salicylate converted the GABA-induced hyperthermia to hypothermia and blocked the release of PGE-like substances.5 Hypothermia induced by GABA alone or in the presence of sodium salicylate was associated with the release of noradrenaline into the effluent.6 Intraventricular administration of GABA in reserpinized dogs produced hyperthermia and not hypothermia. Similar results were obtained with phentolamine perfusion in normal dogs.7 Perfusion with calcium-free solution blocked both the noradrenaline-releasing and hypothermic actions of GABA.8 It is concluded that hyperthermia associated with intraventricular injections of GABA is due to the release of PGE-like substance and hypothermia is due to the release of noradrenaline.

An investigation of alpha-methyl amino-acids and their derivatives on isolated tissue preparations.

1. The ability of alpha-methyl amino-acids and their corresponding amines to restore the sympathomimetic actions of tyramine, and the uptake of the amino-acids and the amines, were studied in isolated tissue preparations obtained from reserpine pretreated animals.2. Tyramine relaxed isolated rat ileum preparations from non-reserpinized rats but not from reserpine treated animals. alpha-Methyldopa, alpha-methylnoradrenaline and lower concentrations of metaraminol restored the responses of reserpinized preparations. alpha-Methyldopamine, alpha-methyl-m-tyrosine, alpha-methyl-p-tyrosine and higher concentrations of metaraminol did not do so. The restoring effect of alpha-methyldopa was blocked by disulphiram. alpha-Methyl-p-tyrosine or alpha-methyl-m-tyrosine blocked the restoring action of alpha-methyldopa but not of alpha-methylnoradrenaline. Cocaine blocked the restoration of responses to tyramine by alpha-methylnoradrenaline but not by alpha-methyldopa. alpha-Methyldopa and alpha-methylnoradrenaline failed to restore responses to tyramine in the presence of sodium-free Tyrode solution.3. Tyramine increased the perfusion pressure in isolated rabbit ear preparations obtained from non-reserpinized animals but was very much less active in preparations obtained from reserpine treated animals. alpha-Methyldopa, alpha-methyl-m-tyrosine, alpha-methylnoradrenaline, alpha-methyl-p-tyrosine and metaraminol restored the effects of tyramine. alpha-Methyldopamine did not do so. The restoring effect of alpha-methyldopa and alpha-methyl-m-tyrosine was blocked by disulfiram. alpha-Methyl-p-tyrosine blocked the restoring effect of alpha-methyl-m-tyrosine.4. Tyramine produced positive inotropic effects in isolated rabbit heart preparations. This was either reduced or absent in preparations obtained from reserpine pretreated animals. alpha-Methyldopa, alpha-methylnoradrenaline, alpha-methyl-m-tyrosine and metaraminol restored the responses to tyramine. alpha-Methyldopamine and alpha-methyl-p-tyrosine did not do so.

3H-metaraminol releasing action of mescaline from rat hypothalamus in vitro.

The amine releasing action of mescaline was investigated in rat isolated hypothalamus labeled with 3H-metaraminol. Mescaline had no effect on the uptake of 3H-metaraminol but produced its release in a concentration-related manner. 4 x 10(-4) M mescaline, which produced submaximal effects was used for subsequent experiments. 3 x 10(-5) M cocaine had no effect on the 3H-metaraminol releasing action of mescaline. Mescaline was fully effective in Ca2+-free medium while 6 x 10(-2) M KCl was ineffective. 3 x 10(-7) M tetrodotoxin or 6 x 10(-5) M lidocaine partially blocked mescaline-induced release but substantially or completely blocked 3 x 10(-2) M KCl-induced release. Prior exposure of hypothalamus to 3 x 10(-4) M tyramine reduced the releasing action of mescaline. Thus, mescaline appears to release 3H-metaraminol both by Ca2+-independent (tyramine-like) and Ca2+-dependent (lidocaine-sensitive) mechanisms. 3 x 10(-4) M tyramine and 6 x 10(-2) M KCl released 14C from control hypothalamus labelled with 14C-mescaline, but not from reserpinized hypothalamus. The amounts of 14C recovered in 14C-mescaline labeled control and reserpinized hypothalamus at the end of 50 min of efflux were similar suggesting a poor retention of 14C-mescaline by storage particles.

Effects on rectal temperature in rats of gamma-aminobutyric acid; possible mediation through putative transmitters.

The rectal temperature of male rats was measured in a thermoneutral environment (25 degrees C) and at ambient temperatures of 15 and 35 degrees C. Unless otherwise specified all drugs were administered intracerebroventricularly (i.c.v.) and all results are reported for the thermoneutral environment. Exposure to 15 degrees C did not affect the rectal temperature but exposure to 35 degrees C produced hyperthermia. At 15 and 25 degrees C, 20 mug GABA produced hyperthermia which was longer lasting at the former ambient temperature. GABA (20 mug) prevented the hyperthermic effect of exposure to 35 degrees C and produced hypothermia in animals maintained at this temperature for 1 hr. A low dose (1 mug) of NA produced hyperthermia and a higher dose (mug) hypothermia. In rats pretreated with sodium salicylate (i.p.), 20 mug GABA and 1 mug NA produced hypothermia instead of hyperthermia, suggesting the release of PGE in mediating hyperthermia. The hypothermic effect of 10 mug NA and of GABA observed at 35 degrees C was blocked by phentolamine, an indication of the possibility of alpha-adrenoceptor mediation.

Evaluation of xanthotoxol for central nervous system activity.

Xanthotoxol (XT), 8-hydroxypsoralen, exhibited dose-graded sedative activity in dogs, cats, rats, mice and hamsters. At doses of 5-20 mg/kg intraperitoneally (i.p.) in cats and 3-100 mg/kg orally (p.o.) in dogs, XT blocked predatory mouse/rat killing behavior. In mice, XT (10-300 mg/kg i.p.) exhibited a dose-dependent reduction in locomotor activity but was less potent in this regard than reference diazepam (10-100 mg/kg i.p.). XT in mice (0.1-10.0 mg/kg i.p.) and in hamsters (0.1-10.0 mg/kg p.o.) antagonized amphetamine-induced hypermobility but was less potent than diazepam. XT elevated the electrical threshold in foot-shock-induced fighting behavior in rats. XT (0.1-30.0 mg/kg p.o.) potentiated pentobarbital-induced narcosis in hamsters at otherwise subeffective doses of pentobarbital. Conditioned avoidance responses in rats were not significantly altered with 1-3 mg/kg i.p. and 30-100 mg/kg p.o. doses of XT but 300 mg/kg p.o. blocked both conditioned and unconditioned response. Doses of 100-1000 mg/kg i.p. of XT in mice were used to study 48-h acute toxicity of XT and its LD50 was estimated to be 468 mg/kg. Doses of 10, 40 and 80 mg/kg p.o. were used to study the chronic toxicity of XT in rats for 6 months and no side effects or abnormalities in reproductive activity or endocrine integrity were noted. The F1 generation of rats from 6-month XT-treated parents were free of teratogenic effects.

Effect of fruits of Moringa oleifera on the lipid profile of normal and hypercholesterolaemic rabbits.

Rabbits were fed Moringa oleifera (200mg/kg/day, p.o.) or lovastatin (6mg/kg/day, p.o.) in banana pulp along with standard laboratory diet and hypercholesterolaemic diet for 120 days. Moringa oleifera and lovastatin were found to lower the serum cholesterol, phospholipid, triglyceride, VLDL, LDL, cholesterol to phospholipid ratio and atherogenic index, but were found to increase the HDL ratio (HDL/HDL-total cholesterol) as compared to the corresponding control groups. Treatment with M. oleifera or lovastatin in normal rabbits decreased the HDL levels. However, HDL levels were significantly increased or decreased in M. oleifera- or lovastatin-treated hypercholesterolaemic rabbits, respectively. Lovastatin- or M. oleifera-treated hypercholesterolaemic rabbits showed decrease in lipid profile of liver, heart and aorta while similar treatment of normal animals did not produce significant reduction in heart. Moringa oleifera was found to increase the excretion of faecal cholesterol. Thus, the study demonstrates that M. oleifera possesses a hypolipidaemic effect.

Effects of Abana, an Ayurvedic preparation, on rabbit atrium and intestine.

The effects of Abana, an Ayurvedic remedy, administered orally to rabbits was studied for its effects on isolated atria and intestine. Administration of Abana for 3 days increased the basal amplitude and reduced the responses of atria to isoprenaline and norepinephrine. Combined treatment with Abana and isoprenaline reduced this effect. It is possible that Abana treatment for 3 days has an action similar to that of chronic administration of isoprenaline (down regulation of beta receptors). A similar down regulation of beta receptors of smooth muscle of rabbit intestine also seems to occur. Abana pretreatment potentiated the inotropic responses of histamine and CaCl2. These effects may be due to a specific depressant effect of Abana on the adrenergic receptors and a direct sensitization of the atrium manifested by an increased response to CaCl2.

Effect of clozapine and molindone on plasma and brain levels of mescaline in mice.

Levels of unchanged mescaline were examined in the plasma and brain of albino Swiss-Webster mice pretreated with various doses of either clozapine or molindone. In clozapine treated mice, the mescaline levels were statistically significantly higher at 2 and 3 h with 7.5 and 15.0 mg/kg and at 1, 2 and 3 h with 30 mg/kg. Molindone at 4.0 and 8.0 mg/kg produced no significant effect; at 16.0 and 48.0 mg/kg, the levels were significantly higher at 1 and 2 h. Elevated brain levels of mescaline by clozapine and molindone indicate an adverse metabolic interaction between a hallucinogen and drugs that are commonly used to treat mescaline-induced psychosis.

Influence of chronic treatment of rats with isoprenaline and calcium channel blockers on response of isolated right ventricle to noradrenaline.

Influence of chronic treatment of rats with and calcium channel blockers (CCBs) and isoprenaline (ISP) on responses to noradrenaline (NA) was investigated on electrically--driven isolated right ventricle preparations. The ventricles were obtained from animals treated with chronic ISP or CCBs alone and chronic nifedipine, verapamil, diltiazem or nimodipine plus chronic ISP. A decreased response to NA as evidenced by an increase in EC50 for contraction which was observed in chronic ISP- treated preparations may be due to development of desensitisation (down-regulation) of beta-adrenoceptors. In chronic CCB-treated preparations there was a significant decrease in the EC50 of NA and decreased contractile response suggesting an increase in the beta-adrenoceptors and decreased availability of calcium, respectively. In chronic CCBs + ISP treated preparations further decreases in the EC50 values were observed suggesting that the voltage gated L-type Ca2+ channels may be affected directly or indirectly by change in beta-adrenoceptor activity. By the above results a proposed mechanism of interrelationship of beta-adrenoceptors with voltage gated L-type calcium channels in cardiac muscle is supported.

Effect of cadmium on contractile response to spasmogens in vascular and nonvascular tissues.

In rat isolated aorta low concentration of CdCl2 (4.8 x 10(-8) M) produced a significant increase in pD2 value of KCl and noradrenaline (NA) with an increase in the maxima, while higher concentration of CdCl2 (1.44 x 10(-5) M) produced a significant rightward shift of the dose-response curve with a depression of maxima. In rat isolated portal vein 4.8 x 10(-7) M CdCl2 produced a significant increase in the pD2 value of KCl with an increase in the maxima, while higher concentration of CdCl2 (4.8 x 10(-5) M) produced a significant rightward shift of the dose-response curve of KCl and NA with a depression of maxima. In rat isolated vas deferens and anococcygeus muscle 4.8 x 10(-8) M CdCl2 produced a significant increase in pD2 value of KCl with an increase in the maxima, while higher concentrations of CdCl2 (4.8 x 10(-6) M and 1.44 x 10(-5) M) produced a significant rightward shift of the dose-response curve of KCl and NA. It is suggested that enhancement and reduction of response to KCl and NA, in presence of different concentrations of CdCl2 might be due to the alteration in the fluxes of calcium ion since these spasmogens produce their action by increasing the availability of calcium ions for the contractile machinery.

Interaction of calcium channel blockers with different agonists in aorta from normal and diseased rats.

The interactions of calcium channel blockers (CCBs) with noradrenaline (NA), phenylephrine (PE), dopamine (DA) and KCl have been investigated in rat isolated aortic strip. In preparations from control and hypertensive (DOCA-saline) rats chronically treated with verapamil, nifedipine and diltiazem, there was partial inhibition of contractions to NA, PE and DA. However, with nimodipine, there was potentiation of responses. This could be related to the occurrence of different isoforms of L-type calcium channels. In preparations obtained from hyperthyroid rats the concentration-response curves of NA, PE and KCl were shifted to the right with depressed maximal response which could be secondary to the primary effect exerted on the heart. In preparations from L-thyroxine + nimodipine/nifedipine treated rats the concentration-response curves of NA, PE and KCl were shifted to the right and the maxima was depressed suggesting that this may be due to decreased alpha receptor density (NA and PE) and down-regulation of voltage operated channels (KCl).