Isolated Frog Heart Research Articles

Cardiac Activity of Isolated Constituents ofInula racemosa

Roots of the plant Inula racemosa are used as folk medicine in east Asia and Europe. Inula racemosa in combination with Commiphora mukul was reported to cure myocardial ischemia. However, systematic investigation of the plant for its specific role in heart diseases has not been conducted so far. In the present study, we have reported the isolation of four major constituents A, B, C and D along with some minor constituents from the plant Inula racemosa. Among the major constituent, constituent Dhas been selected first from spectral data and studied for its cardiac activity on isolated frog heart. The experimental data show that constituent D decreases heart rate and force of contraction at 40 mcg/ml. Actions of Adrenaline are blocked by constituent D and it also acts as an agonist for Propranolol. The studies indicate that constituent D produces a negative ionotropic and negative chronotropic effect on frog's heart. These studies can be utilized as a cardiac marker for exploring the cardiac activity of the plant Inula racemosa.

Johann Nepomuk Czermak and his isolated frog heart.

Johann Nepomuk Czermak and his isolated frog heart.

A New Cardiac Regulator?

Phosphatidylethanolamine-binding protein (PEBP, also called Raf-1 kinase inhibitor protein), which is a precursor to hippocampal cholinergic neurostimulating peptide (HCNP), is found in various tissues, including brain, adrenals, and platelets. Noting that PEBP and HCNP have been found in synaptic vesicles and that HCNP is secreted by hippocampal neurons, Goumon et al. investigated the possible localization of these peptides in adrenal chromaffin cells (which are related developmentally and functionally to sympathetic neurons and, when stimulated, release catecholamines into the blood). The authors used a combination of techniques to show that PEBP could be found in the cytoplasm and the secretory granules of cultured bovine adrenal chromaffin cells. Stimulation of the cells with increased extracellular concentrations of K + or with nicotine led to PEBP release into the extracellular solution with a similar time course and nicotine concentration dependence as for release of chromagranin A (a known constituent of chromaffin granules). PEBP was also secreted by platelets treated with thrombin receptor-activating peptide and could be detected in bovine serum. The authors used two-dimensional liquid chromatography-tandem mass spectrometry to show that HCNP was also present in chromaffin granules. Suspecting a possible endocrine role--and based on the known effects of catecholamines and the chromagranin A-derivative vasostatin I--the authors examined the effects of HCNP on isolated frog heart and discovered that it decreased stroke volume and stroke work and counteracted the positive inotropic effects of the β-adrenergic agonist isoproterenol. Thus, HCNP may represent a new endocrine modulator of cardiac physiology. V. Goumon, T. Angelone, F. Schoentgen, S. Chasserot-Golaz, B. Almas, M. M. Fukami, K. Langley, I. D. Welters, B. Tota, D. Aunis, M.-H. Metz-Boutigue, The hippocampal cholinergic neurostimulating peptide, the N-terminal fragment of the secreted phosphatidylethanolamine-binding protein, possesses a new biological activity on cardiac physiology. J. Biol. Chem . 279 , 13054-13064 (2004). [Abstract] [Full Text]

Antihypertensive Activity of the Total Alkaloids from the Leaves of Moringa oleifera

Moringa oleifera leaves have traditionally been used in Ayurvedic medicine for their antihypertensive activity. Preliminary studies in our laboratory indicated that a water extract of leaves of this tree is efficacious in reducing the chronotropic and inotropic effects on the isolated frog heart. The alkaloids obtained by the fractionation of the water extract of the leaves of M. oleifera, converted into their salt form, were tested for their activity on the isolated frog heart. The total alkaloidal salts were found to have a negative inotropic effect on the frog heart. This activity was further characterised by testing it on the isolated guinea pig ileum.

Peptide TSKY Decelerates Outcome of the Ground Squirrel from Hibernation

Effect of peptide TSKY on the heart rate was studied in the ground squirrel Citellus undulatus at outcome from hibernation. At provocation of awakening in the first half of the hibernation bout (the 3rd–4th hibernation days), an intraperitoneal peptide injection at a dose of 1 mg/kg produced a deceleration of the HR increase and elongated the time of transfer of the animal to the normothermia state. This effect was not observed in the second half of the hibernation bout (the 5th–7th hibernation days). The study of the peptide cardiotropic activity on an isolated frog heart did not reveal any statistically significant TSKY activity.

Scilla maderensis, TLC screening and positive inotropic effect of bulb extracts

Scilla maderensis Menezes (Hyacinthaceae) is endemic to the Portuguese Archipelago of Madeira. The taxonomic proximity between Scilla L. and Urginea Steinh. genus, and also the knowledge that bulbs of Urginea maritima (L.) Baker ( Scilla maritima L.) contain cardiac glycosides of the bufadienolide type, led us to a phytochemical and pharmacological study of S. maderensis. Extracts obtained from the bulbs were screened by TLC and tested in the isolated frog heart preparation. The TLC screening revealed spots with colours and R f values similar to those obtained for proscillaridin and scillaren A. In the frog heart preparation the extracts showed a positive inotropic effect and toxic doses induced the arrest of the heartbeat in systole. We can conclude that the bulbs of S. maderensis contain substances exerting pharmacological effects on the heart.

Luigi Luciani and the earliest graphic demonstration of Wenckebach periodicity.

Using an isolated frog heart preparation with ligatures around the atria, Luigi Luciani, an Italian physiologist working in 1873 in Carl Ludwig's famous laboratory in Leipzig, was the first to demonstrate cardiac group beating, which he named periodic rhythm. He attributed this to increased resistance to impulse propagation between the atria and the ventricle. Karel F. Wenckebach, in his 1899 landmark report of group beating in a patient in which he also used pulse tracings, credited Luciani with this discovery. Wenckebach referred to the phenomena as "Luciani periods." With the advent of electrocardiography in the early 20th century, this form of group beating became known as Wenckebach periodicity and then as Mobitz type I atrioventricular block. We reanalyzed Luciani's original paper and pulse tracings, and we show that periodic rhythm does indeed meet the criteria of second-degree atrioventricular block as established by Wenckebach. We also reviewed the career of Luciani, who was an important investigator, outstanding teacher and mentor, and distinguished leader of 19th-century physiology. We conclude that Wenckebach still deserves to have his name eponymously attached to this type of atrioventricular block because he was the first to unravel the complicated relationship between atrial and ventricular conduction.

Hepatoprotective And Cardiac Inhibitory Activities Of Ethanolic Extracts From Plant Leaves And Leaf Callus Of Eclipta Alba

The present study deals with hepatoprotective activity observed with ethanolic extracts of plant leaves and leaf callus of Eclipta alba (L.) Hassk. The model used was carbon tetrachloride (CCl 4) -induced acute hepatotoxicity in albino rats. In addition, cardiac inhibitory activity on isolated frog heart was examined. Liver damage was assessed by quantifying serum activities such as serum glutamate pyruvate transaminase (SGPT), serum glutamate oxaloacetate transaminase (SGOT), serum albumin, serum total protein, serum alkaline phosphatase (ALPH), liver weight and histopathological examination. The results indicated that oral administration of ethanolic extracts at the dose levels of 250 mg/kg and 300 mg/kg, respectively, exhibited a significant hepatoprotective effect on carbon tetrachloride-induced liver injuries. Hepatic lesions caused by CCl 4 were improved by treatment with both ethanolic extracts, and were compared to Amlycure (commercial Indian herbal hepatoprotective formulation) as a standard reference medicine. When examined for cardiac inhibitory activity with isolated frog heart, i.e., the extracts showed negative ionotropic and negative chronotropic effects as well as reduction in cardiac output. Callus extract (20 mg) produced a higher cardiac inhibitory activity than that of leaf extracts (20 mg). Furthermore, the callus extract was found to antagonise the effect of adrenaline. Plant leaves and leaf calli contain coumestans including wedelolactone and demethylwedelolactone.

Micromachined biosensor terminals for the study of growing neurons

Since 1972, micromachined plastic and silicon sensors have been developed at Cardiff. In planar mode, they have been used as cultivation surfaces for human neural blastoma cells and Chinese Hamster ovarian cancer cells, and recording platforms for isolated frog heart (54 channels with terminals down to 4 μm diameter). In probing mode, they have been used to record neural activity in honeybee brain and frog sciatic nerve (12 channels with terminals down to 1 μm diameter on a variety of probes down to 3×3×100 μm). In enclosure mode, these sensors are being developed with holes etched through the microterminals to allow neural and bacterial cells to grow within each terminal aperture (12 channels with apertures down to 5 μm diameter on probes down to 30×50×500 μm). These devices have been modified by the addition of biochemical-compatible surfaces to create sensors for the monitoring of a wide range of medically important analytes, especially oxygen, glucose and a range of neurotransmitters. The probes are micromachined with chemical etchants, plasmas, ion beams and laser beams. Sculptured carbon surfaces and electropolymerised pyrrole, for the attachment of enzymes, are illustrated.

Effect of Azadirachta indica hydroalcoholic leaf extract on the cardiovascular system

1. 1. The effect of Azadirachta indica hydroalcoholic leaf extract on the cardiovascular system was studied. 2. 2. The leaf extract was found to reduce a dose-dependent hypotensive effect without altering the amplitude or rate of respiration. 3. 3. In isolated frog heart, there was no noticeable change in amplitude of contraction or rate of the heart at lower doses of leaf extract. However, at higher doses, there was temporary cardiac arrest in diastole. 4. 4. The results are discussed.

Cardiomodulating actions of low-molecular peptides from various groups

A total of 61 low-molecular peptides belonging to various groups was tested and compared for their cardiomodulating potentials usingin situ isolated frog hearts, and some neuropeptides among them showed marked cardiomodulating activity, as was evidenced by the substantial alterations they caused in the recorded parameters of strophanthin K cardiotoxicity.

P-680 - The role of phosphoinositide system in thrombin-induced positive inotropic effects in isolated frog hearts.

P-680 - The role of phosphoinositide system in thrombin-induced positive inotropic effects in isolated frog hearts.

Influence of pre-, post-, and simultaneous perfusion of elevated calcium on the effect of ascending concentrations of lead on digoxin-induced cardiac arrest in isolated frog heart

Cardiotoxicity of lead, a ubiquitous environmental pollutant, has already been documented as a potentially lethal, although rarely recognized, complication of lead intoxication. Further, it has already been reported from this laboratory that lead acetate (LA) preperfusion potentiated cardiotoxicity of digoxin (DGN) in isolated frog heart preparation and that exposure to elevated calcium (elev. Ca{sup 2+}) prior to, and simultaneously with LA at 10{sup {minus}7} M concentration, attenuated this potentiation. As an extension of this work, it was considered of interest to study the effect of perfusion of elev. Ca{sup 2+} (6.5 mM) prior to, after and simultaneously with ascending concentrations of lead (10{sup {minus}9}, 10{sup {minus}7} and 10{sup {minus}5}M) on DGN induced cardiac arrest (CA) in isolated frog heart, since Pb{sup 2+} and Ca{sup 2+} ions are known to compete with each other for the same target sites at the cellular level, an instance of competitive mass action effect. 15 refs., 1 fig., 1 tab.

Cardiovascular effects of the aqueous extract of Moringa pterygosperma

AbstractThe aqueous extract of stem bark of Moriga pterygosperma (Family Moraingaceae) was investigated for its effect on various pharmacological parameters. In cardiovascular profile at lower concentrations (1–10 ng) it produced a dose dependent positive inotropic effect (n = 3, 1.29 ± 0.021 for 10 ng) and at higher concentrations (0.1–1 μg) a dose dependent negative inotropic effect (n = 3, 0.53 ± 0.033 for 1 μg) on the isolated frog heart. It also produced a dose dependent hypotensive effect on dog blood pressure (n = 3, 82 ± 0.98 for 20 mg/kg). It failed to elicit any effect on isolated guinea‐pig ileum, rat stomach fundus or frog rectus abdominis muscle.

The use of isolated functional heart to pharmacologically characterize active ingredients in the aqueous extracts of Mareya micrantha

Aqueous extracts of Mareya micrantha are used as folk medicine in West Africa. However, no systemic investigation directed to the identification of the active ingredients in M. micrantha has been done. Therefore, this study investigated the effects of M. micrantha on the cardiac contractility of the isolated frog heart. Also, two sequential fractions from M. micrantha were separated and their effects on cardiac contractility investigated. M. micrantha concentration-dependently suppressed cardiac contractility. Separation of the cardioactive components in series by column chromatography (Sephadex G-50, Column 2.5 × 30 cm and 1 × 20 cm) produced two fractions which facilitated a leftward shift of the dose-response curve of the cardiodepressant effects suggesting that column chromatograph is effective in the isolation of the cardioactive ingredients in M. micrantha. The data suggest that M. micrantha contains cardioactive components and that contractions of the isolated functional frog heart can be used as a pharmacological activity marker during the process of isolation of cardioactive ingredients in M. micrantha.

Hypotensive activity of ovatodiolides isolated from a Chinese crude drug ‘Fáng Féng Cáo’

AbstractMacrocyclic diterpenoids, ovatodiolides, showed a transient hypotensive activity in the anaesthetized dog. The effects of ovatodiolides on the activity of angiotensin converting enzyme (ACE), contactile activity in isolated frog heart by the Yagi‐Hartung method and the Ca2+ current measured with the voltage clamp method in single bullfrog atrial cells were examined. Ovatodiolide (1) showed inhibitory activity of myocardial contraction and an antagonistic effect on Ca2+ current. These results suggest that the hypotensive activity by ovatodiolides at least, partly, may be due to inhibition of myocardial contraction.

Calcium antagonists. A role in the management of cyanide poisoning?

The physiological role of calcium was demonstrated by Ringer (1883) when he linked the omission of calcium (Ca++) from the bathing medium to the induction of cardiac arrest in the isolated frog heart. This observation established that Ca++ controlled muscle contraction but it was not until the autumn of 1963 that the specific pharmacological significance of this contribution was realised by Fleckenstein (1964), leading to the development of Ca++ antagonism as a concept in drug action (Fleckenstein 1977). Identifying the precise role of Ca++ ions in toxic cell injury and tissue death attributable to drug and chemical intoxication has lagged behind developments in Ca++ physiology and pharmacology and to date, much remains to be learned, although studies aimed at characterising the role of Ca++ in cytotoxic cell injury are receiving intense attention (Bondy Komulainen 1988; Maduh et al. l988a, l99Oa,b; Orrenius et al. 1989; Trump et al. 1989). On the other hand, the importance of cyanide as a poison has been known from antiquity (for references to earlier literature see Baskin Fricke 1992; Solomonson 1981). In experimental cyanide poisoning, recent studies have examined alterations in cell Ca++ and the influence of Ca++ antagonists in the management of this chemical toxicologicalmore » emergency. These efforts have principally focused on the cellular Ca++ homeostasis system, its interrelationship with cellular components, and its susceptibility to cyanide action.« less

A force transducer and a length-ramp generator for mechanical investigations of frog-heart myocytes.

An apparatus for studying the mechanics of isolated frog heart myocytes is described. The cells are held horizontal in a through of Ringer solution by means of two suction micropipettes. Myocyte force is measured with an opto-electronic system recording the deflection of the tip of one micropipette, which acts as a cantilever force probe. The force probes are selected for compliance according to the force a myocyte is expected to develop in a given condition, so as to limit myocyte shortening during force development to no more than 1% of the slack cellular length (l0). The other micropipette, which is stiff relative to the forces measured, is mounted on an electromagnetic-loudspeaker motor by which controlled-velocity length changes, of preset size and in either direction, are imposed on myocytes. The force transducer has a sensitivity of 5-10 mV/nN, with a frequency response of 700-900 Hz in Ringer solution and a resolution of 0.5-1 nN. The motor with a suction micropipette can complete controlled-velocity length ramps within 1.5-2.0 ms, across a range of +/- 100 microns at a resolution of 8.0 nm. These values correspond, for frog-heart myocytes 200 microns and 400 microns long, to 25%-50% l0 and 0.002%-0.004% l0 respectively.

Influence of pre- and simultaneous perfusion of ascending concentrations of lead on the effect of elevated calcium on digoxin-lnduced cardiac arrest in isolated frog heart

Lead is a toxic metal that occurs ubiquitously in modern times as an environmental pollutant. It remains a significant health hazard as human exposure to it, has been steadily increasing with progressive industrialization. Cardiotoxicity is already documented as a potentially lethal, although a rarely recognized complication of lead intoxication (Myerson and Eisenhauer 1963; Freeman 1965; Khan et al. 1967; Silver and Rodriguez Torres 1968; Williams et al. 1983). It has already been reported that lead preperfusion potentiated cardiotoxicity of digoxin (DGN) a widely prescribed cardiotonic drug in human beings in isolated frog heart preparation (Krishnamoorthy et al. 1987).

Effect of preperfusion of ascending concentrations of lead on digoxin-induced cardiac arrest in isolated frog heart

The present work investigated the effect of preperfusion of ascending concentrations of lead acetate (LA) (10 −9, 10 −7 and 10 −5 M) on digoxin (DGN) cardiotoxicity in isolated frog heart, in order to look for any consequent variations in its lead-induced potentiation. The DGN perfusion time (s) and DGN exposure (μg DGN 10 mg heart weight) for, and myocardial DGN level (ng DGN g wet tissue) at, cardiac arrest were the parameters evaluated so as to assess cardiotoxicity. Both sodium acetate and LA (10 −7 M) preperfusion led to a diminution in cardiac rate at 10 min of DGN perfusion without altering the contractility compared to the DGN alone group. With regard to DGN perfusion time for cardiac arrest, preperfusion of ascending concentrations of LA induced a corresponding decrease which was statistically significant ( P <0.05). On the other hand, in the experimental group that received preperfusion of 10 −9 M LA, the DGN exposure for cardiac arrest was not significantly different from that of the control, whereas in the 10 −7 and 10 −5 M groups, it was significantly lower ( P <0.05). In the experimental group that received preperfusion of 10 −7 M LA, the significant reduction in DGN perfusion time and DGN exposure was well corroborated by a diminution in the myocardial DGN level (4.01 ± 0.17 ng g wet tissue in comparison with the control value of 5.72 ± 0.4 ng g wet tissue, P < 0.05) at cardiac arrest. Taken together, these data reveal that with the preperfusion of LA in ascending concentrations, there is a relative increase in LA-induced potentiation of DGN cardiotoxicity. The present findings may be partially explained by the reported competition between Pb 2+ and Ca 2+ ions at the cellular level, with the consequent antagonism of calcium-stimulated cardiac contractility and myofibrillar protein phosphorylation, and also by the inhibitory effect of lead on (Na +,K +)-ATPase, and binding of digitalis to this enzyme.