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Biomedical subjects

H Venkatakrishna-Bhatt

Publications and source records attributed to H Venkatakrishna-Bhatt.

At least 19 recordsLinked to original sources
PubMed1999

Potentiation of acetylcholine-induced smooth muscle contraction in rat ileum by lead.

The aim of this study was to find out lead interaction on acetylcholine-induced ileal (0.8 "to 1" longitudinal total strips) contractions in varying calcium (Ca++) or magnesium (Mg++) media and the cholinergic mechanism. Potentiation of ileal strips by lead (Pb++) remained dose-dependent as elicited by acetylcholine-induced contractions (1.81 x 10(-6) M to 1.28 x 10(-4) M). These were completely antagonized by atropine (1.01 x 10(-8) M). Lead (1.2 x 10(-5) M) potentiated contractions caused by acetylcholine in normal or in excess Ca++ media, but in low Ca++ or with various Mg++ media, lead failed to potentiate such contractions. Thus Pb++ has indirect cholinomimetic effect which involved extracellular Ca++.

Acetylcholine↗
PubMed1993

Magnesium and reserpine influence norepinephrine sensitivity of vas deferens in rats.

Reserpine induced supersensitivity to norepinephrine (NE) in rat vas deferens was sought by alteration of Mg++ and Ca++ concentration in incubation medium in the absence and presence of EDTA. Vas deferens incubated in Mg++ free and Mg++ excess media showed supersensitivity and subsensivity to NE respectively. Alterations in the sensitivity to NE produced by varying the concentrations of Mg++ were comparatively less. In the presence of EDTA, vas deferens obtained from reserpinized animals showed subsensitivity in normal and Mg++ excess media and supersensitivity in Mg++ free medium. In the presence of EDTA, reserpinized preparations showed slight supersensitivity in normal Mg++ medium, marked supersensitivity in Mg++ free and lesser subsensitivity in Mg++ excess medium. Probably EDTA by more effectively removing Mg++ from the membrane binding sites by chelation makes the membrane permeable to Ca++ leading to supersensitivity to NE (observed only in the presence of EDTA). These results suggest that the failure of reserpine to induce supersensitivity to NE in rat vas deferens may be due to an enhanced antagonism of Mg++ on Ca++ movements in this preparations due to the poor capacity of rat tissue to retain Ca++.

Animals↗
PubMed1993

Effect of lead on anorexia and body weight in albino rats.

Rats exposed to lead (lead acetate) in doses of 0.2 and 0.5 mg/ml in drinking water for a period of 90 days showed mild to moderate changes in food consumption compared to control group. Drug interactions in lead exposed rats with metoclopramide, atropine sulphate, propranolol, cyproheptadine and mepyramine maleate when administered intraperitoneally caused -30 to +30 percentage variation in food intake indicating the influence of adrenergic, serotonergic and cholinergic neurotransmitters with no change in mean body weight of lead treated rats.

Administration, Oral↗
PubMed1993

Carbon disulphide induced sensitivity changes of rat anococcygeus muscle to noradrenaline (NA).

The sensitivity of rat anococcygeus muscle to noradrenaline (NA) was reduced following carbon disulphide (CS2) pretreatment. Preparations incubated in excess Ca++ (4.2 mmol.L-1) or Zero Ca++ (0.0 mmol.L-1) media showed decrease in sensitivity to NA. Reserpinization failed to induce supersensitivity to NA in any Mg++ concentration in the media. Reserpinized tissue in Mg++ free media with EDTA showed increased sensitivity while decreased sensitivity and maximum response to NA in Mg++ (1.2 mmol.L-1) and excess Mg++ (3.6m mol.L-1) concentration of the medium. In the presence of EDTA, the inhibition observed with CS2 in excess Mg++ (3.6m mol.L-1) medium was comparatively much less in both non-reserpinized and reserpinized preparations. In normal Ca++ and its deficient medium decrease in sensitivity to CS2 and the relevant maximum response to NA were observed. In excess Ca++, the CS2 effect depressed corresponding to its maximal response to NA. Thus CS2 may be inhibiting responses to NA by interfering with Ca++ utilization.

Animals↗
PubMed1992

Effect of lead on the blood serum, liver and brain sialoglycoconjugate levels in rats.

Rats were exposed to an acute dose of lead (Pb) to study the effect of Pb intoxication on different sialoglycoconjugates in serum, brain and liver. Serum levels of total sialic acid (TSA), perchloric acid (PCA)-soluble sialic acid (PSA), lipid-bound sialic acid (LBSA), free sialic acid (FSA) and alpha 1-acid glycoprotein (alpha 1-AG) were determined. They were also estimated in brain and liver tissues, except for LBSA and FSA. All these constituents were found to be significantly raised in the serum but not in the brain. In the case of the liver, only alpha 1-AG levels were found to be increased significantly, the rest were not altered. The levels of these sialoglycoconjugates in serum might be useful as biomarkers of heavy metal toxicity.

Animals↗
PubMed1992

In vitro study of rat uterus after chronic formaldehyde exposure.

To measure cholinergic, adrenergic and tryptaminergic receptor activity of formaldehyde (HCHO) in rat uterus, albino rats were treated with 5 and 10 mg/kg, ip HCHO for 30 days. Acetylcholine (ACh) in doses 1.33, 2 and 3 micrograms/ml produced mild to moderate contraction of isolated rat uterus in control group. HCHO had no effect on isolated rat uterus per se, however it reduced ACh and carbachol induced contraction and presence of adrenaline influences in respect of ACh and carbachol activity. Adrenaline per se had no effect in control preparations, but reduced carbachol induced contraction. Propranolol had no effect on rat uterus; but its presence in the bathing medium increased activity of adrenaline. 5-Hydroxytryptamine (5-HT) had no effect of its own on isolated rat uterus but its presence in the bathing medium enhanced contractions of carbachol and oxytocin.

Animals↗
PubMed1991

Inhibitory effect of lead on 5-hydroxytryptamine induced contractions of isolated ileum of rat.

The present study examined the effects of lead (Pb) on the 5-hydroxytryptamine (5-HT) contracture and calcium (Ca++) kinetics of ileum of rat. Isolated ileum preparations incubated in excess Ca++ (2.8 mM) or in Ca++ free Tyrode solution showed decrease in sensitivity to 5-HT. The inhibitory action of Pb reduced the sensitivity and decrease maximum responses to 5-HT in any Mg++ concentration of the medium. In the normal Ca++ and its deficient medium deterioration in sensitivity to Pb and the relevant maximum response to 5-HT were observed. In excess Ca++, the Pb effect depressed corresponding to its maximal response to 5-HT. The presence of EDTA depressed the Pb effect irrespective of the Ca++ influence on the receptors. Thus Pb may be inhibiting responses to 5-HT by interfering Ca++ utilization.

Animals↗
PubMed1989

Influence of trace metals on serum total sialic acids and perchloric acid--soluble proteins and sialic acids in mice.

Male Swiss mice were exposed to a single LD50 (75%; i.p.) of mercury, zinc, lead and manganese to determine their influence on serum sialic acid and protein levels after a refractory period of 48 h. They significantly elevated, in different proportions, the serum levels of total and perchloric acid (PCA)-soluble sialic acids (biological marker) and PCA-soluble proteins, thus indicating their toxicity.

Animals↗
PubMed1989

Effects of hexachlorocyclohexane (HCH) on the contractile response induced by norepinephrine in the rat isolated vas deferens.

Effects of hexachlorocyclohexane (Technical HCH) on the contractile responses of rat isolated Vas deferens to norepinephrine (NE) were investigated by varying the Ca++ and Mg++ concentrations of the incubation medium. Preparations incubated in excess Ca++ (4.2 mM) or in Ca++-free Krebs solution showed decrease in sensitivity to NE. The inhibitory action of HCH reduced the sensitivity and decreased maximum responses to NE in any Mg++ concentration of the medium. In the normal Ca++ and its deficient medium decrease in sensitivity to HCH and the relevant maximum response to NE were observed. In excess Ca++, the HCH effect depressed corresponding to its maximal response to NE. The presence of EDTA depressed the HCH effect irrespective of the Ca++ influence on the receptors.

Animals↗
PubMed1989

Histological and pharmacological changes in vas deferens of rats exposed to hexachlorocyclohexane.

The effect of hexachlorocyclohexane (HCH) treatment in male albino rats at dosages of 3 and 6 mg/kg body weight by force-feeding were studied over a period of 180 days. Histological observations revealed graded degeneration in the muscular layer of vas deferens. Moreover, the accumulation of HCH residue in serum and vas deferens is highly significant in the experimental group. The contractility of muscles showed marked inhibition by in vitro study.

Administration, Oral↗
PubMed1989

Pharmacology of Acorus calamus L.

Water soluble dried powder of alcoholic extract of roots and rhizomes of A. calamus L. was used. The in vivo experiments involved strychnine convulsant activity in frogs, spontaneous motor activity and amphetamine hyperactivity in mice, pentobarbitone sleeping-time in rats and local anaesthetic activity in guinea pigs and rabbits. Frog skeletal muscle and heart preparations and rat phrenic nerve diaphragm constituted the in vitro experiments. Plant extracts at 10, 20 mg/kg ip did not afford protection to strychnine (1,5,2.5 mg/kg) induced convulsions and same effect was found on acetylcholine induced contractions of rectus muscle except that it inhibited caffeine citrate contractions in frog. At 1, 10 and 100 micrograms/ml doses, it caused negative iono- and chronotropic effects in frogs. Dosages of 10, 25, 50 mg/kg ip of herbal extract antagonize spontaneous motor activity and also amphetamine induced hyperactivity in mice. It was less potent than chloropromazine, though exerts sedative and tranquilizing action. Local anaesthetic activity was found to be absent at 0.5 and 1% dose levels.

Animals↗
PubMed1988

Effect of Momordica charantia Linn. pomous aqueous extract on cataractogenesis in murrin alloxan diabetics.

The fruit extract of Momordica charantia Linn. was studied in Charles Foster rats of both sexes in respect of its dose-response hypoglycemia and at maximal effective dose, its influence on the development of diabetic cataract. Alloxan (120 mg/kg s.c./rat, single dose) diabetic rats with greater than 150 mg% of blood sugar were classified into four groups (n = 10) wherein two were control and the rest were test groups). In the test group, the oral dose response hypoglycemic herbal effect was found to be maximum at 4 g/kg/Day/rat when administered for 20 days. This dose was continued in the 2nd test group for a period of 2 months. Blood sugar in all the rats was estimated by microdetermination method using a dextrometer before and after therapy. The control group of rats received 2 ml of 0.9% NaCl and they developed cataract in 90 to 100 days. The herbal treated diabetics showed cataract in 140 to 180 days. Cataract formation was found to be dependant on blood sugar levels since the control group with blood sugar 307 +/- 81 (mg%) was blind 2 months earlier than herbal treated group which showed blood sugar 149 +/- 66.37 (mg%).

Animals↗
PubMed1988

Folklore therapeutic indigenous plants in periodontal disorders in India (review, experimental and clinical approach).

Though a number of plants and their parts are used for dental ailments among population in rural and urban areas of developing countries, in India however, the most common house-hold, road-side plants are mango (Mangifera indica), neem (Azadirachta indica; Melia azadirachta), ocimum (Ocimum basilicum), tea-dust (Camellia sinensis) and uncommonly murayya, i.e., currey leaf (Murayya koenigi) [Chopra et al. 1958, Kirtikar and Basu 1935, Nadakarni 1954, Satyavati 1984]. The leaves of these plants are folded and brushed (massage with teadust) against the teeth. Therefore, the present study is restricted only to the fleshy leaf extracts [Jindal et al. 1975] (except tea) of these plants inspite of certain limitations in the methodology and arbitrations in the microbial identification and isolation in the light of recent advances in folk dentistry. The investigation was carried out in two parts: 1) Experimental study: The efficacy of various dentifrices (commonly available in the market) and the potentiating effect of the leaf extract (LE) of the aforesaid indigenous plants when amalgamated with the tooth-paste against pathogens, were investigated. Further, the protection afforded by the said plant extracts (PE) over the conventional allopathic medicines on the human plaque cultures and gram negative bacteria from patients were studied. 2) Clinical study: The therapeutic effects of the said PE (individually) on clinical application among severely infected patients were examined.

Humans↗