meta-iodobenzylguanidine uptake in the hypertensive-diabetic rat heart: a marker for myocardial dysfunction?

The purpose of this study was to investigate the cardiac adrenergic neuronal changes induced by diabetes and hypertension by using an analogue of norepinephrine, meta-iodobenzylguanidine (MIBG), and to compare these changes with the contractile state of ventricular papillary muscle. The tissue concentration of norepinephrine in the cardiac apex was also measured for direct comparison with [123I]MIBG uptake. One week following the induction of diabetes by streptozotocin injection (55 mg/kg, i.v.), male Sprague-Dawley rats were given subcutaneous injections of a hypertension-inducing agent, deoxycorticosterone acetate (DOCA, 25 mg/kg), or DOCA vehicle twice weekly for 3, 6, 9, or 12 weeks. At the end of each time point, the animals were injected intravenously (15 mCi/mg; 1 Ci = 37 GBq) with [123I]MIBG. The results showed a progressive decrease in MIBG uptake into the hearts of diabetic, hypertensive, and diabetic-hypertensive rats during the 12-week observation period, compared with the control group. However, length-tension papillary muscle studies at 12 weeks indicated that only the diabetic group had a diminished performance compared with control. Furthermore, an inverse relationship was observed between MIBG uptake and norepinephrine levels in the cardiac apex of the diabetic and diabetic-hypertensive groups. Therefore, we concluded that either MIBG does not provide an accurate indication of adrenergic integrity or that there is no relationship between sympathetic activity and myocardial function at the time points measured. MIBG did not prove to be a useful marker for myocardial dysfunction in diabetic rats.

Fructose loading induces cardiovascular and metabolic changes in nondiabetic and diabetic rats

The effects of fructose loading on the integrated cardiovascular function in vivo, glycemic control, glucose tolerance, and plasma lipid levels in nondiabetic and streptozotocin (STZ) diabetic rats were investigated. Endothelial morphology of the thoracic aorta was also assessed with scanning electron microscopy. Fructose-loaded nondiabetic rats exhibited elevated blood pressure and pulse rate, and signs of arterial atherogenesis, such as focal adherence of leukocytes and fibrin to the endothelium. Intraperitoneal glucose tolerance tests revealed a greater increase in plasma insulin in response to glucose challenge in these animals than in the control. Compared with the untreated STZ-diabetic animals, fructose-loaded diabetic rats had significantly greater hyperglycemia, glucose intolerance, and hyperlipidemia and higher blood pressure, but had a similar degree of hypoinsulinemia, cardiac dysfunction, and cardiac enlargement. They also showed signs of early atherogenesis. The central venous pressure and the susceptibilities of the rats to the induction of ventricular arrhythmias by intravenous infusion of aconitine were not significantly affected by either STZ injection or fructose loading. It is concluded that prolonged intake of an excessive amount of fructose has detrimental effects on the cardiovascular system, glucose metabolism, and plasma lipid levels in both nondiabetic and STZ-diabetic rats.

Cardiovascular and metabolic changes in spontaneously hypertensive rats following streptozotocin administration

OBJECTIVES

To investigate whether the high mortality rate that occurs in streptozotocin (STZ)-diabetic spontaneously hypertensive rats (SHR) is related to abnormalities in glycemic control, in hemodynamics and cardiac function, or in susceptibility to the occurrence of ventricular arrhythmias.

METHODS

Diabetes was induced in SHR and Wistar-Kyoto (WKY) rats by the intravenous injection of STZ 55 mg/kg. Intraperitoneal glucose tolerance tests were performed after six and 11 weeks. Blood pressure was measured in conscious rats at weeks 0 and 11 with a tail-cuff method and in anesthetized animals at week 12 through a cannulated artery. Response of myocardial function to rapid intravenous infusion of saline 10 mL/kg/min and the times of onset of ventricular arrhythmias during intravenous infusion of aconitine 20 micrograms/kg/min were determined in anesthetized rats at week 12. Plasma samples from the rats were assayed for glucose, insulin, triglycerides and carnitine.

RESULTS

STZ injection caused hyperglycemia, hypoinsulinemia and glucose intolerance equally in SHR and WKY. Diabetic SHR exhibited significant hypertriglyceridemia, depletion in plasma carnitine, impaired responses of blood pressure and myocardial function to rapid intravenous infusion of saline and a 37.5% mortality rate, whereas diabetic WKY did not exhibit these changes. SHR and WKY, diabetic or nondiabetic, were equally sensitive to the induction of ventricular arrhythmias by aconitine infusion.

CONCLUSION

Mortality of the STZ-diabetic SHR is not due to an exaggeration of the impaired glycemic control, but may be attributed to the occurrence of cardiac dysfunction. The development of life-threatening cardiac arrhythmias, while unlikely, cannot be completely excluded.

[Clinical application of rhombotrapezious island musculocutaneous flap for skull base and/or craniomaxillary operation with malignant tumor]

Regional pedicled musculocutaneous flaps are the mainstay of the head and neck reconstruction. They provide a rapid, highly reliable and single-staged technique that is applicable in most cases. The rhombotrapezious island musculocutaneous flap is valuable in the base and craniomaxilloface reconstruction. In this study we updated our experience with the rhombotrapezious island musculocutaneous flap (RTIMF) in 6 cases from 1989 to 1993. Dissections were performed on 9 cadavers, 4 preserved and 5 fresh, yielding 18 pairs or dorsal scapular and transverse cervical artery for evaluation. In the five fresh cadavers, the arteries were selectively cannulated and injected with colored latex. 67% with dorsal scapular and transverse cervical artery commonly arose from the thyro-cervical trunk. 33% with the dorsal scapular artery directly arose from the second part of the subclavian artery. In the period of 1989-1993, 6 rhombotrapezious island musculocutaneous flaps with vascularized pedicle were used for immediate repair in the skull base or craniomaxillary cancer operations. There was no complication of the flaps. Donor site complications were relatively minor. The disturbance in shoulder function was well tolerated. We advocated the incorporation of both the greater and lesser rhomboid muscle to form the compound rhombotrapezious flaps to enhance the vascular supply to the overlying skin. The major advantage of the RTIMF are that it provides a long paddle of thin pliant, hairless skin and muscle that can be rotated as far as the craniomaxilloface and scalp in a single stage. It offers the longest arc of rotation and thus the greatest versatility for the skull base or craniomaxillary reconstruction.

Integrated cardiovascular function in the conscious streptozotocin-diabetic deoxycorticosterone-acetate-hypertensive rats

Blood pressure, heart rate, and left ventricular function were measured in conscious diabetic Sprague-Dawley rats subjected to 5 weeks of deoxycorticosterone acetate (DOCA) treatment which was started 1 week following intravenous injection of streptozotocin (STZ) (60 mg/kg) to induce diabetes mellitus. It was found that chronic administration of DOCA in nondiabetic animals caused an increase in blood pressure and functional parameters of left ventricle, and a decrease in heart rate and plasma insulin levels. Normotensive diabetic rats exhibited hyperglycemia, hypoinsulinemia, and a lower body weight as compared with control animals but did not show significant abnormalities in cardiovascular function. DOCA-hypertensive STZ-diabetic rats had similar hyperglycemia, milder hypoinsulinemia, and a significantly lower rate of left ventricular relaxation and systolic blood pressure compared with the nondiabetic DOCA-hypertensive animals. It is concluded that the addition of DOCA hypertension to intact 6-week STZ-diabetic Sprague-Dawley rats results in the occurrence of cardiac dysfunction.

Neuroimaging and neuropathologic findings in AIDS patient with cytomegalovirus infection

This 21-year-old male with hemophilia A developed cytomegalovirus (CMV) retinitis associated with acquired immunodeficiency syndrome (AIDS). He had a history of numerous blood transfusions. Serum antibody titers became positive for human immunodeficiency virus (HIV), when the patient was 18 years of age. Three years later, he developed CMV retinitis due to his immunosuppression. Ganciclovir (DENOSINE, TANABE SEIYAKU CO., LTD., Osaka, Japan) therapy given for 4 weeks produced a marked improvement in the ocular fundal findings, but the neurologic signs and symptoms, including headache, hypoesthesia, disorientation, and dementia became worse. T2-weighted magnetic resonance imaging (MRI) demonstrated a diffuse high intensity area in the periventricular white matter and small focal or patchy lesions in the hippocampus, basal ganglia, midbrain, medulla oblongata and the nucleus dentatus. The patient died of HIV encephalopathy and CMV infection. Characteristic CMV intranuclear inclusion bodies were observed histologically in most sites of the brain including the hippocampus, white matter, basal ganglia, midbrain, medulla oblongata, nucleus dentatus and the retina. Infiltration by monocyte-macrophage and multinucleated giant cells, which are characteristic of HIV encephalopathy, were observed in the periventricular white matter and the hippocampus. In this patient, the neuroimaging findings were compatible with the neuropathologic observations. MR imaging proved useful in detecting the central nervous system (CNS) lesions of AIDS and CMV infection.

One-year treatment of non-diabetic and streptozotocin-diabetic rats with vanadyl sulphate did not alter blood pressure or haematological indices

Circulatory and haematological effects of chronic administration of vanadyl sulphate in drinking water for one year in non-diabetic and streptozotocin-diabetic rats were investigated. At various time points during the treatment period and at 13 weeks following its withdrawal, systolic blood pressure and pulse rate were measured using a tail-cuff method and some selected haematological indices, including haematocrit, haemoglobin, erythrocyte count, reticulocyte percentage, leukocyte count, platelet count, and leukocyte composition of the peripheral blood were determined using standard methods. It was found that prolonged treatment of either nondiabetic or streptozotocin-diabetic rats with vanadyl sulphate did not cause significant changes in the parameters observed but significantly alleviated the occurrence of bradycardia and the decreased leukocyte count in the peripheral blood in streptozotocin-diabetic animals. No significant changes in systolic blood pressure, pulse rate, or haematological indices were observed following the withdrawal of vanadyl sulphate, except that the previously vanadyl-treated diabetic rats were found to have higher leukocyte count, platelet count and neutrophil percentage, and lower lymphocyte percentage in their leukocyte composition. It is concluded that vanadyl sulphate does not have a hypertensive effect nor is it significantly toxic to the haemopoietic system in rats.

One-year treatment of streptozotocin-induced diabetic rats with vanadyl sulphate

Streptozotocin-diabetic and non-diabetic rats were given various concentrations of vanadyl sulphate in drinking water for one year. It was found that vanadyl sulphate caused significant decreases in body weight gain and plasma insulin level in non-diabetic rats, but did not significantly alter fluid and food intakes or plasma levels of glucose, triglycerides, or cholesterol. In diabetic animals, vanadyl treatment significantly alleviated or prevented the occurrence of hyperglycaemia, hypoinsulinaemia, hyperphagia, polydipsia, hyperlipidaemia, or cataract formation, but the slower body weight gain was not improved. There were gradual decreases in the intake of the compound required to correct hyperglycaemia in the values of ED50 with age of the rats. The beneficial effects of vanadyl treatment persisted 16 weeks following the withdrawal of the compound. It is concluded that vanadyl sulphate is an effective agent for chronic therapy of streptozotocin-induced diabetes in rats, and its prolonged use does not lead to the development of tolerance.

Hemodynamic and nonhemodynamic mechanisms of experimental pulmonary edema in rats and the effects of anisodamine and tetramethylpyrazine--estimation of blood gas analysis, RBC superoxide dismutase and prostaglandin E2 in plasma and bronchoalveolar lavage (Part 3)

Anisodamine (ADM, 654-2, 30 mg/kg) and tetramethylpyrazine (TMP, 120 mg/kg) have shown an apparent preventive effect on pulmonary edema (PE). In this study, the nonhemodynamic mechanism was studied: The dynamic changes of PaO2, O2Sat, PaCO2, and blood pH were measured, and RBC superoxide dismutase (SOD) and plasma and bronchoalveolar lavage (BAL) PGE2 levels were estimated. It was concluded that ADM and TMP exerted inhibitory effects on the hypoxic state. The ability of ADM and TMP to adjust RBC SOD and PGE2 levels may be one of the preventive mechanisms of the drugs.

Hemodynamic and nonhemodynamic mechanism of experimental pulmonary edema in rats and the effect of anisodamine and tetramethylpyrazine--electron microscopic observation and measurement of pulmonary arterial, pulmonary arterial wedge and systemic arterial pressure (Part 2)

The pulmonary edema (PE) induced by adrenaline (AD) administration is similar to neurogenic PE. Anisodamine (ADM, 654-2, 30 mg/kg) and tetramethylpyrazine (TMP, 120 mg/kg) have shown significant preventive effects. Electron microscopic observation was carried out to study the changes of microvascular permeability, and the dynamic change of mean pulmonary arterial pressure (PAP, 40 rats), mean pulmonary arterial wedge pressure (PAWP, 20 rats) and mean carotid arterial pressure (CAP) were also measured. The results suggested that both ADM and TMP have significant inhibitory effects on PAWP and CAP increase, as well as on the damage responsible for the increase of microvascular and alveolar permeability.

[Histochemical studies on the glycoconjugates of experimental alkali burned cornea in rabbit]

The model of experimental alkali burn of cornea in rabbit was obtained using 1 mol/L NaOH solution. After being burned for 1, 3, 7 and 14 days, the histochemical changes of these models were studied by using labelled concanavalin A (ConA-FITC) and wheat germ agglutinin (WGA-FITC). The results showed that after being burned, the amount of glycoconjugates interacted with these lectins decreased, and increased gradually after 7 days, then reached the level higher than that in the normal cornea. These changes were related to the recovery of alkali burned cornea.

Hemodynamic and nonhemodynamic mechanisms of experimental pulmonary edema in rats and the effect of anisodamine and tetramethylpyrazine. Part 1: Survival rate, pulmonary index, pathological change and pulmonary vascular permeability

Pulmonary edema (PE) which is similar to the neurogenic type was induced by adrenaline (AD) administration (0.1 mg/kg) in rats. Acute progressive respiratory distress, cyanosis and dyspnea occurred. All the experimental animals in the PE group died within 20 min after AD injection, with a pulmonary index (PI) of 1.70 +/- 0.47 (mean +/- S) which was much higher than that in the normal group. The mortality rate was 100%. It was found that in rats with PE, a protein-rich fluid filled the alveolar and interstitial spaces, and ecchymosis occurred. The capillary permeability as estimated by Evans blue injection showed that Evans blue from extraction fluid and bronchoalveolar lavage (BAL) in the PE rats was at a much higher level than that in the normal control (NC) rats. In anisodamine (ADM, 654-2) and tetramethylpyrazine (TMP) treated rats, almost all the damage was diminished or absent, and the mortality rates were decreased from 100% to 4.4% and 20%, respectively. 654-2 and TMP could significantly inhibit the increase of pulmonary permeability.

[Effect of occupation on health behavior and biological cardiovascular risk factors]

Within the framework of the second survey of MONICA-Switzerland (cantons of Vaud and Fribourg; canton of Tessin), the data of 683 working men were analysed to examine the relation between occupation and cardiovascular risk factors. For this purpose, lifestyle factors (smoking, nutritional habits, physical activity, alcohol intake) as well as blood pressure and serum lipoprotein concentrations were compared among 17 different occupational groups. Furthermore, every occupational group was ranked, based on the medians of the mentioned dependent variables. A strong relationship between socioeconomic status (recorded as number of years of schooling completed) and an index for healthy lifestyle was found. However, in some occupational groups a major discrepancy between socioeconomic status respectively lifestyle and measured cardiovascular risk factors (blood pressure, lipoprotein concentrations) was observed. It is therefore hypothesized that unknown occupational factors adversely affect blood pressure and serum lipoproteins for example in physicians, managers and executives whereas the contrary--beneficial effect of unknown occupational factors--is true for example for drivers and bricklayers.

Effects of fructose loading in streptozotocin-diabetic and nondiabetic rats

The present study compares the cardiovascular consequences of a 6-week fructose feeding in nondiabetic and streptozotocin-diabetic rats. Myocardial performance of these animals was determined using the isolated perfused working heart preparation. Systolic blood pressure, pulse rate, ventricular weight/body weight ratio, and plasma levels of glucose, insulin, triglycerides, and cholesterol were measured. In nondiabetic rats, fructose drinking caused significant increases in blood pressure, pulse rate, and plasma concentrations of insulin and triglycerides. Streptozotocin-diabetic animals exhibited significantly less body weight growth, slower pulse rate, higher plasma levels of cholesterol and triglycerides, ventricular enlargement, and functional impairment of the myocardium. The fructose-loaded diabetic rats had larger increases in plasma cholesterol and triglycerides than did control fructose-fed rats, but the fructose-induced increases in blood pressure and pulse rate were attenuated significantly. However, plasma levels of glucose and insulin and the degree of ventricular enlargement and myocardial dysfunction were not significantly different from those of control diabetic rats. These results show that fructose loading for 6 weeks can cause increases in blood pressure, pulse rate, and plasma lipids in both nondiabetic and diabetic rats. However, fructose ingestion does not significantly alter glycemic control or affect the development of myocardial dysfunction in streptozotocin-diabetic rats.

[Morphology and delta-endotoxin proteins of Bacillus thuringiensis from soils and their toxicities to insects]

94 strains of Bacillus thuringiensis were isolated from soils in southwest and northwest of China. The morphology of cells, spores and parasporal crystals of these strains was investigated under transmission and scanning electro-microscope. Proteins of delta-endotoxins from all strains were analysed by rapid SDS-PAGE. 9 species of insects in Lepidoptera, Coleoptera and Diptera were tested for assay of delta-endotoxins. Some kinds of parasporal crystals were quite different in form and in composition of protein from those reported before. Most of strains were nontoxic to all of 9 species used in bio-assay. Some strains were very effective in species of Coleoptera or Noctuidae.

Myocardial performance of STZ-diabetic DOCA-hypertensive rats

Myocardial performance of streptozotocin (STZ)-diabetic deoxycorticosterone acetate (DOCA)-hypertensive rats was examined using the isolated working heart apparatus at various time periods after induction of the experimental diseases. Blood pressure, pulse rate, and plasma levels of glucose, insulin, cholesterol, and triglycerides, as well as ventricular weight-to-body weight ratio, were also determined. In nondiabetic rats it was found that DOCA hypertension was associated with an increase in plasma cholesterol, a decrease in circulating insulin level, lower weight gain, and ventricular enlargement compared with control rats. Diabetic rats developed myocardial dysfunction in a time-dependent manner and exhibited hyperglycemia, hypoinsulinemia, bradycardia, and ventricular enlargement. Compared with the normotensive diabetic animals, STZ-diabetic DOCA-hypertensive rats showed a similar magnitude of myocardial dysfunction and a greater degree of ventricular enlargement, but significantly less severe hyperglycemia. It is concluded that DOCA-induced hypertension does not aggravate the severity of myocardial dysfunction developed in STZ-diabetic rats. It is also suggested that DOCA may have an action on glucose metabolism either directly or via an effect on insulin secretion.

Effects of deoxycorticosterone acetate on glucose metabolism in nondiabetic and streptozotocin-diabetic rats

A previous study in our laboratory showed that streptozotocin (STZ) induced diabetic, deoxycorticosterone acetate (DOCA) induced hypertensive rats exhibited significantly lower levels of plasma glucose than did normotensive diabetic animals. The present experiments further investigate the effects of DOCA treatment on fasting levels of plasma glucose and insulin and on their changes after oral glucose challenge in nondiabetic and STZ-diabetic rats. It was found that, in nondiabetic rats, DOCA-induced hypertension was associated with normal glucose levels and glucose tolerance but with significantly lower levels of plasma insulin. DOCA-treated diabetic animals showed significantly lower levels of plasma glucose, but their plasma insulin concentrations were not significantly different from those of the DOCA vehicle treated diabetic rats. DOCA-treated diabetic rats also had significantly higher plasma levels of cholesterol and triglycerides. It is suggested that DOCA may have a direct or indirect action on the assimilation, production, or utilization of glucose, perhaps leading to an improvement in insulin sensitivity and subsequently a decrease in insulin secretion.

Blood pH and the actions of nifedipine on cardiac excitation-contraction coupling

Hearts from male Sprague-Dawley rats were perfused, by the Lagendorff method, with calcium-free Krebs solution (containing either adrenaline or a high level of potassium) at pH 7.48 (control), 7.26 (acidosis) or 7.69 (alkalosis). When the hearts stopped contracting, a dose of nifedipine or its vehicle was given before measuring the force of contraction, coronary perfusion pressure and heart rate in response to graded doses of calcium. The calcium-antagonising efficacy of nifedipine was reduced during acidosis in both adrenaline- and potassium-stimulated hearts, but the reduction was greater in the adrenaline-stimulated hearts. Alkalosis led to a small increase in the efficacy of nifedipine on adrenaline- and potassium-stimulated contractions.

A pseudo-Poisson noise model for simulation of positron emission tomographic projection data

Although radioactive decay obeys Poisson statistics, because of the corrections that are applied to the projection data prior to reconstruction, the noise in positron emission tomography (PET) projections does not follow a Poisson distribution. Use of Poisson noise when simulating PET projections in order to test the performance of reconstruction and processing techniques is therefore not appropriate. The magnitude of PET projection noise was observed to be as much as 10 to 100 times greater than Poisson noise in some instances. A quadratic function was found to fit the relationship between noise power spectral density and total projection count. The coefficients of the quadratic function were determined for projections of different tracer distributions and types. Using these observations, a method of simulating PET projections was developed based on a pseudo-Poisson noise model. Projections simulated according to this method are good approximations to real projection data and take into account the characteristics of individual PET cameras and particular tracer distributions. Such simulated projections have been valuable in predicting the performance of reconstruction algorithms. This approach can also be applied to single photon emission tomography.

Role of peptido-leukotrienes in the genesis of early ventricular arrhythmias during acute myocardial ischaemia in rats

Changes in cardiac ventricular concentrations of peptidoleukotrienes (peptido-LTs) following coronary artery ligation and the effects of lipoxygenase inhibition and leukotriene antagonism on the cardiovascular responses to acute myocardial ischaemia were studied in pentobarbitone-anaesthetised rats. It was found that the left ventricular peptido-LT levels significantly increased at 2.5 and 5 min after left coronary artery ligation while the changes in right ventricle were not statistically significant. Pretreatment with nordihydroguaiaretic acid 25, 50 or 100 mg/kg caused marked depletion of ventricular peptido-LT content, but did not significantly prevent the blood pressure or heart rate changes, the occurrence of ventricular tachycardia or fibrillation, or the mortality of the animals following coronary artery ligation. Administration of SK&F 102922, even at doses which caused marked decreases in blood pressure and heart rate, also did not significantly alter the cardiovascular changes and the mortality rate induced by left coronary artery ligation. It is, therefore, suggested that the occurrence of ventricular arrhythmias and haemodynamic changes during the early phase of acute myocardial ischaemia may not be due to the augmented synthesis of peptido-LTs in cardiac tissue.

Circulatory depression and ventricular arrhythmias induced by compound 48/80 in anaesthetized rats

The effects of graded doses of compound 48/80 on various cardiovascular and respiratory parameters were studied in pentobarbitone-anaesthetized rats. Following intravenous injections, this compound significantly depressed the mean blood pressure (MBP), left ventricular pressure (LVP) and dLVP/dtmax, and caused ventricular tachycardia (VT) or fibrillation (VF) and death. Heart rate (HR) response were variable, and there were no marked changes in airway resistance or blood gases. Pretreatment of the animals with either cimetidine or diphenhydramine significantly prolonged the time of onset of VT/VF but failed to alter the changes in other circulatory variables. A combination of cimetidine and diphenhydramine significantly alleviated the decreases in MBP and LVP and prevented the occurrence of VT/VF. It is suggested that the circulatory depression and the occurrence of ventricular arrhythmias following the administration of compound 48/80 result from activation of H1- and H2-receptors by elevated blood histamine levels due to release of the amine from tissues.

[Cardiovascular risk factors of visitors to a mass-screening booth]

The attitude towards mass screening of serum cholesterol is controversial. In order to characterize the volunteers of such screenings and to test the representativity of its findings, we compared the data of 1686 adult health-screening participants collected during a trade fair in the city of Basel, Switzerland, with the results of two population-based studies, the Basel City Risk Factor Survey and the MONICA Project in Western Switzerland. Among those screened, there was an over-representation of women and older persons. The age-specific medians of blood cholesterol and proportions of hypercholesterolemic persons were consistently higher in female screenees--and marginally so in males--than in the reference populations, whereas higher proportions of persons with ideal cholesterol level in those screened were also observed, especially in younger males. Higher systolic blood pressure, lower relative body weight and less regular smoking were found consistently among the screenees. This cross-sectional study shows that the participants of such mass screening actions are a selective group of older, more frequently female health-conscious persons with a specific risk-factor pattern. Mass screenings of self-selected volunteers can, therefore, not be used for a reliable prediction of risk-factor distributions in the general population. Moreover, suggested further steps for those screenees with both health-conscious behavior and elevated biological risk-factor levels, such as second measurement, medical consultation and counselling, cannot be assured in the setting of a trade fair. The objectives and intentions of such mass screening activities should be reconsidered and discussed.

In-vivo and in-vitro studies on the effects of chronic dexamethasone treatment on cardiovascular responses to sympathetic stimulation

Rats treated with dexamethasone, 1.5 mg/kg s.c. weekly for 3 weeks exhibited significantly greater increases in mean arterial pressure than their controls, following either sympathetic nerve stimulation or noradrenaline administration. The atria from dexamethasone-treated rats showed greater chronotropic activity in response to noradrenaline but not to field stimulation, whereas the force of contraction was significantly less than that of the controls after either field or noradrenaline stimulation. Isolated rat tail artery preparations from dexamethasone-treated rats were found to be twice more sensitive to noradrenaline than the controls. Prazosin antagonised the noradrenaline-induced pressor response to the same extent in control and dexamethasone-treated rats. Dexamethasone treatment did not significantly increase the sensitivity to KCl or the angiotensin-potentiated pressor response to noradrenaline. This study shows that dexamethasone treatment increases postsynaptic sensitivity of the cardiovascular system to noradrenaline in rats.

Naloxone-induced cardiovascular depression in rats that had received chronic morphine-treatment

1. Cardiovascular changes in response to intravenous injection of naloxone were studied in pentobarbitone-anaesthetized rats which had been given morphine in their drinking water for 1-21 days. The mechanisms of the observed changes were investigated in intact animals and in isolated hearts and tail arteries. 2. In rats that had received chronic morphine-treatment, intravenous administration of naloxone caused immediate decreases in blood pressure, heart rate, left ventricular pressure and dLVP/dtmax which were followed by the occurrence of atrial or ventricular extrasystoles and other signs of opiate withdrawal such as faecal passage and muscle twitching. 3. The intensities of the naloxone-precipitated cardiovascular changes were directly related to the duration of chronic morphine pretreatment, reaching statistically significant levels on day 2 or 3 and maximal levels on day 7 or 14. This phenomenon disappeared on days 3 to 14 following opiate withdrawal in animals which had been treated previously with morphine for 21 days. 4. Either atropine or clonidine pretreatment significantly prevented the occurrence of faecal passage or muscle twitching during naloxone-precipitated opiate withdrawal. However, clonidine, but not atropine or yohimbine, abolished the decreases in various haemodynamic parameters. The occurrence of cardiac extrasystoles was not affected. 5. In isolated heart or tail artery preparations from chronically morphine-treated rats, naloxone administration did not elicit reactions which differed from those of the preparations from naive animals. These findings suggest that under pentobarbitone anaesthesia, the cardiovascular systems of rats that had received chronic morphine treatment exhibit inhibitory, instead of excitatory, reactions to naloxone-precipitated opiate withdrawal.

Influence of pH changes on the actions of verapamil on cardiac excitation-contraction coupling

Langendorff preparations of Sprague-Dawley rat hearts were perfused with calcium-free Krebs solution of pH 7.48 (control), 7.26 (acidosis) or 7.69 (alkalosis) containing either adrenaline or potassium. The responses of the force of contraction, coronary perfusion pressure and heart rate to graded doses of calcium preceded by a single dose of verapamil were measured. Contractile responsiveness to calcium was reduced during acidosis in both adrenaline- and potassium-stimulated hearts but was increased or reduced during alkalosis with adrenaline- or potassium stimulation, respectively. The efficacy of verapamil as a calcium antagonist increased during acidosis or alkalosis in both adrenaline- and potassium-stimulated hearts. In conclusion, acidosis or alkalosis inhibits potassium-stimulated contractions of the heart and enhances the effects of verapamil on potassium- and adrenaline-mediated contractions. Acidosis inhibits and alkalosis enhances adrenaline-stimulated contractions.

Cardiovascular responses to nifedipine in anaesthetized rats with abnormal blood gas/pH levels

1. Blood pressure and pulse rate responses to intravenously (i.v.) administered nifedipine were studied in chloralose-anaesthetized rats subjected to hypoxaemia, hyperoxaemia, alkalosis, acidosis, hypocarbia with alkalosis, or hypercarbia with acidosis. 2. Ventilation with a gas mixture of 17% O2, 28% O2, or 23% O2 with 5% CO2 at a fixed stroke volume (10 mL/kg) and rate (80 strokes/min) induced hypoxaemia, hyperoxaemia or hypercarbia, respectively. Hypocarbia was induced by ventilation with 17% O2 at 160 strokes/min. Acidosis or alkalosis was produced by intravenous infusion of 1 mol/L HCl or 1 mol/L NaHCO3, respectively, in animals ventilated with room air. 3. There were significant decreases in blood pressure and pulse rate during acidosis, and increases in pulse rate during alkalosis and hypercarbia. No marked changes in these parameters were observed under the other experimental conditions. 4. The control animals showed a dose-dependent decrease in blood pressure without marked changes in pulse rate in response to nifedipine injection. 5. Significant reductions in the hypotensive effect of nifedipine were observed in rats subjected to alkalosis, acidosis, or hypercarbia. A similar tendency was also found during hypocarbia while the responses to nifedipine during hypoxaemia and hyperoxaemia were statistically the same as those in the controls. 6. It is concluded that alterations of blood pH reduce the hypotensive effect of nifedipine, and we suggest that blood pH changes probably play a more important role than PO2 or PCO2 abnormalities in altering the cardiovascular responses to nifedipine in hypoventilated or hyperventilated rats.

[Total cholesterol, HDL-cholesterol and blood pressure in relation to life style: results of the first population screening of the Swiss MONIKA Project]

To evaluate the association of individual health habits with levels of cardiovascular risk factors such as serum cholesterol and blood pressure, data from a representative population sample of 860 men and 788 women, aged 25 to 64 years and residing in Western Switzerland, were analyzed cross-sectionally. The data had been collected during 1984/85 as a part of the WHO MONICA project, an international research project on the epidemiology of cardiovascular diseases. In age-adjusted analysis, a score of prudent diet was a reasonably strong inverse correlate of total cholesterol in men (p less than 0.001) but less so in women (p = 0.11); the diet score was unrelated to HDL cholesterol. In both genders, alcohol consumption was associated with elevated levels of systolic and diastolic blood pressure (men: both p less than 0.001; women: p = 0.05 and 0.01 respectively) and of HDL cholesterol (men and women: p less than 0.001). Coffee consumption was unrelated to either blood lipids or blood pressure. In both men and women, leisure-time exercise was a predictor of a low-risk lipid profile, i.e. a low total cholesterol/HDL ratio (both p less than 0.001). Better educated persons, especially women, revealed consistently lower levels of cardiovascular risk factors. The independent character of these lifestyle-risk factor-associations was largely confirmed in a multivariate analysis, with cigarette smoking emerging as another significant predictor of a deteriorated lipid profile, while education was not an independent determinant of biological risk factors. Lifestyle variables, including body mass index, explained 9 to 19% of variance in cardiovascular risk factors, with relative weight being the strongest of the predictors related to behaviour. Entering age and sex into the regression models enhanced the predictive power of the equations to 16 to 26% explained risk factor variance. We conclude from this population-based, cross-sectional study that personal health habits such as diet, exercise, alcohol consumption and smoking, as well as body weight are significantly and independently related to blood lipid and blood pressure levels; the apparent size of effect of these behavioural traits on biological risk factors for cardiovascular diseases was only modest, but it may nevertheless be relevant to prevention.

Age-related differences in the cardiovascular responses to haemorrhagic shock in rats

The cardiovascular responses to haemorrhagic shock were studied in male Sprague-Dawley rats of different age groups, ranging from 6-15 weeks (body weight 250-460 g). Haemorrhagic shock was induced by bleeding (2% body weight), under urethane anaesthesia, from the cannulated femoral artery at a rate of 1 ml/min. It was found that the younger rats had significantly smaller values of left ventricular pressure and dLVP/dtmax following haemorrhage and a greater mortality rate. Older animals exhibited significantly greater falls in blood pressure and pulse rate during the bleeding procedure, and slower recovery in these parameters after the bleeding was stopped. However, these rats had a significantly higher left ventricular pressure and dLVP/dtmax following haemorrhage, and a markedly lower mortality rate. The findings demonstrate the existence of age-related cardiovascular responses to haemorrhagic shock in rats.

[Survey of Bacillus thuringiensis and Bacillus sphaericus from soils of four provinces of China and their principal biological properties]

A number of isolates of Bacillus thuringiensis and Bacillus sphaericus were obtained from soils of Southwestern Area and Shaanxi Province of China. Among isolates of B. thuringiensis were under 13 sorts of serotype in total of 23 sorts of B. thuringiensis and about 20% of auto-agglutinate strains. Rules of ecologic distribution of two sorts of bacteria were analysed. Toxicities on six species of insects, morphology and crystal proteins of B. thuringiensis, as well as toxicities, morphology and crystal proteins of B. sphaericus, were investigated. 22 strains of more efficient of B. thuringiensis and 2 strains of more efficient of B. sphaericus were obtained. It was shown that B. thuringiensis is actually soil microorganism, and resource of B. thuringiensis is much fruitful in Southwestern Area of China.

Effects of blood gas/pH abnormalities on the cardiovascular actions of verapamil in rats

1. The effects of hypoxaemia, hyperoxaemia, alkalosis, acidosis, hypocarbia with alkalosis or hypercarbia with acidosis on the blood pressure and pulse rate responses to verapamil were studied in chloralose-anaesthetized rats. 2. At a fixed stroke volume (10 mL/kg) and rate (80 strokes/min; except for the hypocarbic group at 160 strokes/min), hypoxaemia, hyperoxaemia, hypercarbia with acidosis, or hypocarbia with alkalosis was induced by artificial ventilation with gas mixtures containing 17% O2, 28% O2, 23% O2, with 5% CO2, or 17% O2, without CO2 respectively. Acidosis or alkalosis was produced by intravenous infusion of 1 mol/L HCl or 1 mol/L NaHCO3 respectively, in animals artificially ventilated with room air. 3. Changes in individual blood gas/pH parameters had no significant effect on blood pressure except for acidosis which caused a significant decrease. Effects on pulse rate were significant increases in the alkalosis and hypercarbia groups, decrease in the acidosis group, while in other conditions no significant changes were recorded. 4. In the controls, intravenous injections of verapamil 20-320 micrograms/kg caused dose-dependent increases in mean blood pressure, while effects on pulse rate were not marked. 5. The hypotensive responses to verapamil were significantly alleviated or enhanced in the presence of alkalosis or acidosis respectively. Verapamil also caused greater falls in pulse rate during acidosis. Effects of Po2 changes were not statistically significant. The influence of PCO2 changes remained unclear. 6. The present findings suggest that changes in blood pH may play a more important role than Po2 alterations in affecting the cardiovascular responses to verapamil in the presence of blood gas abnormalities.

Cardiovascular responses to verapamil and nifedipine in hypoventilated and hyperventilated rats

1. The influence of hypoventilation or hyperventilation on blood pressure and pulse rate responses to verapamil and nifedipine was studied in chloralose-anaesthetized rats. 2. Artificial ventilation with room air at a fixed volume of 10 ml kg-1 successfully induced combinations of hypoxaemia, hypercarbia and acidosis at a ventilator rate of 37 strokes min-1 and of hyperoxaemia, hypocarbia and alkalosis at 160 strokes min-1. 3. Hypoventilation caused significant decreases in both the blood pressure and pulse rate, whereas hyperventilation produced significant increases in these parameters. 4. In the controls, intravenous injections of graded doses of either verapamil or nifedipine caused dose-dependent decreases in mean blood pressure. The effects on pulse rate were not marked. 5. The hypotensive effects of verapamil were significantly more intense in hyperventilated rats, whereas those of nifedipine were significantly less pronounced in hypoventilated animals. The hypoventilated rats exhibited a significant dose-dependent decrease in pulse rate in response to verapamil administration. 6. It is concluded that cardiovascular responses to verapamil, nifedipine and probably other calcium antagonists are altered in the presence of blood gas abnormalities.

Ventricular histamine concentrations and mast cell counts in the rat heart during acute ischaemia

The ventricular histamine concentrations and mast cell counts of naive and disodium cromoglycate-treated rats subjected to acute left coronary artery ligation under pentobarbitone anaesthesia were examined. In naive animals, there was a significant increase in the right ventricular histamine level at 2 min following left coronary artery ligation. Left ventricular histamine concentrations tended to decrease, and were significantly lower than those of the right ventricle at 5 min. However there were no significant changes in mast cell counts of the right or left ventricles after left coronary artery ligation. Treatment with disodium cromoglycate did not significantly alter the ventricular mast cell counts, interfere with the changes in ventricular histamine concentrations, or the occurrence of early ventricular arrhythmias and haemodynamic changes in response to acute left coronary artery ligation. It is suggested that the increase in the right and decrease in the left ventricular histamine concentrations during acute myocardial ischaemia involves mainly the non-mast cell stores, instead of mast cell sources, of cardiac histamine.

Changes in preganglionic sympathetic nerve function following chronic morphine treatment in rats

1. The effects of acute or chronic morphine treatment on the changes in blood pressure and pulse rate in response to ganglionic stimulation or blockade and to vagal stimulation, and of isolated atria to field stimulation or noradrenaline, were studied. 2. In pithed rats, intravenously injected hexamethonium significantly depressed the blood pressure responses to sympathetic nerve stimulation. The ganglionic blocking effects of hexamethonium were significantly greater in chronically morphine-treated rats, but were not significantly affected by acute morphine administration in naive animals. 3. Intravenous administration of nicotine dose-dependently increased blood pressure and pulse rate. The magnitudes of these changes were not significantly affected by acute or chronic morphine pretreatment. 4. Studies with rat isolated atrial preparations revealed that the changes in atrial contractile rate and force in response to noradrenaline or field stimulation were not influenced by either acute or chronic morphine treatment. 5. Cervical vagal stimulation produced voltage- or frequency-dependent decreases in pulse rate and blood pressure. The responses were not significantly affected by chronic morphine treatment. 6. These findings suggest that the site of the changes in sympathetic function following prolonged exposure to the opiate appears to be on the preganglionic nerve fibres.

Histamine enhances hypoxia-induced ventricular arrhythmias in isolated rat hearts

1. The effects of hypoxia, histamine-receptor agonist perfusion, and their combination on cardiac rhythm were studied in isolated rat hearts. 2. While hypoxia induced a high incidence of ventricular tachycardia or fibrillation, only a few preparations developed ventricular arrhythmias in response to perfusion with high concentration of histamine, 2-pyridylethylamine or impromidine. 3. The times of onset of hypoxia-induced ventricular arrhythmias were significantly shortened by perfusion with either histamine, 2-pyridylethylamine or impromidine. The accelerated occurrence of hypoxia-induced ventricular arrhythmias by histamine was significantly abolished by pretreatment with either diphenhydramine or cimetidine. 4. The results indicate that hypoxia and histamine can increase ventricular vulnerability of the rat heart to each other. It is also suggested that the arrhythmogenic actions of histamine in hypoxic rat hearts are mediated by both histamine H1-and H2-receptors.

Anaesthetic-related occurrence of early ventricular arrhythmias during acute myocardial ischaemia in rats

The cardiovascular responses of rats anaesthetised with different anaesthetic agents to acute coronary artery ligation were studied. Before thoracotomy, urethane-anaesthetised animals exhibited significantly lower blood pressures. Ligation of the left coronary artery induced a high incidence of ventricular tachycardia or fibrillation in rats anaesthetised with pentobarbitone, urethane, or ether inhalation followed by chloralose. Ketamine-anaesthetised animals had a significantly lower incidence of ventricular arrhythmias. The mortality rate was also lower, though not statistically significant. However, all groups of rats showed essentially similar blood pressure and heart rate changes following coronary artery ligation as well as the time of onset of ventricular tachycardia or fibrillation. The findings demonstrate the influence of anaesthetics on the occurrence of early ventricular arrhythmias following acute coronary artery ligation in rats.

Morphine treatment and intravenous glucose tolerance tests in mice

The effect of acute and chronic morphine treatment on i.v. glucose tolerance tests in mice was investigated. It was found that neither acute nor chronic morphine treatment affected the serum glucose disappearance with time after i.v. glucose loading, indicating that morphine has no significant effect on glucose tolerance. Analysis of hepatic glycogen and glucose levels in these mice revealed that morphine treatment might have some effects on glucose metabolism, but at the analgesic dose employed, did not impair the animal's physiological response to i.v. glucose loading.

Heroin self-administration by rats: influence of dose and physical dependence

Lever-pressing behavior reinforced by intravenous infusion of various concentrations of heroin, and consequent development of physical dependence, were examined in rats. In addition, the influence of opiate dependence, and of its disappearance following withdrawal, on heroin self-administration were investigated. It was found that intravenous self-administration of heroin at 0.03 mg/kg/infusion maintained self-administration behavior without producing physical dependence. Total responses per session decreased with increasing unit dose of heroin, whereas the total amount of drug self-administered was directly related to unit dose. Significantly greater numbers of withdrawal signs and percentage body weight losses in response to naloxone injections were observed following self-administration of heroin at 0.1, 0.3 or 0.6 mg/kg/infusion. Intake of heroin at 0.03 mg/kg/infusion, but not at 0.1, 0.3 or 0.6 mg/kg/infusion, was found to increase significantly in opiate-dependent and postdependent animals. These findings support the previous use of 0.03 mg/kg/infusion as a suitable dose for illustrating the reinforcing effect of heroin without the influence of physical dependence.

Arterial catecholamine levels in morphine-treated rats subjected to sympathetic nerve stimulation

1. The effect of acute or chronic morphine treatment on the changes in arterial noradrenaline and adrenaline levels in response to sympathetic nerve stimulation was studied in rats. 2. Rats which had been chronically treated with morphine in their drinking fluid for 21 days were shown to be morphine-tolerant, as revealed by the tail-immersion test for analgesia. 3. It was found that animals given either acute or chronic morphine treatment had similar basal concentrations of arterial catecholamines to their controls. 4. Sympathetic nerve stimulation produced significant increases in arterial noradrenaline and adrenaline levels in both the control and morphine-treated animals. However, the degree of arterial noradrenaline elevation was significantly less in morphine-tolerant animals. 5. This phenomenon was not observed in acutely morphine-treated rats or at 2 weeks following opiate withdrawal in animals which had been treated previously with morphine for 3 weeks. 6. The findings suggest that chronic morphine treatment in rats not only leads to opiate tolerance but also reduces catecholamine release in response to sympathetic nerve stimulation.

Plasma, cardiac tissue and brain morphine concentrations in acute and chronic morphine-treated rats

1. The plasma, cardiac tissues and brain morphine concentrations in rats after acute or chronic morphine treatment were measured by high-performance liquid chromatography. 2. Morphine concentrations in plasma and cardiac tissues were found to be significantly higher than those in brain after acute morphine injection. However, after chronic oral administration, morphine concentrations in plasma, cardiac tissues and brain were similar. 3. Brain concentrations of morphine following chronic administration were higher than those obtained after acute administration although concentrations in plasma and cardiac tissues were lower.

Influence of acute myocardial ischaemia on ventricular cyclic AMP concentrations in naive and morphine-treated rats

1. Ventricular cyclic AMP (cAMP) concentrations of naïve and morphine-treated rats subjected to acute myocardial ischaemia were examined. 2. In naïve rats, ventricular cAMP levels were increased at 3 min but decreased 5 and 10 min after left coronary artery ligation. Statistically significant changes were observed in the right ventricle after 3 min and in the left ventricle after 10 min. 3. Acute morphine treatment did not significantly alter ventricular cAMP content in rats subjected to either sham operation or acute left coronary artery ligation. 4. Ventricular cAMP concentrations were significantly lower in sham-operated rats after 5 weeks of chronic morphine treatment while after 3 weeks of chronic morphine treatment, this phenomenon was seen only after acute coronary ligation. The reductions were reversed by opiate withdrawal. 5. These observations support the theory that elevated cAMP levels may contribute to the production of early ventricular arrhythmias during acute myocardial ischaemia. It is suggested that the reduction in ventricular cAMP concentrations may partly account for the previously reported decreased occurrence of early ventricular arrhythmias in chronic morphine-treated rats subjected to acute left coronary artery ligation.

Ventricular histamine concentrations in naive and morphine-treated rats during acute myocardial ischaemia

The ventricular histamine concentrations of naive and morphine-treated rats subjected to acute left coronary artery ligation were examined. In naive animals, there was a significant increase in the right ventricular histamine level at 5 min following ligation, but not at 3 or 10 min. Left ventricular histamine concentrations tended to decrease, but the changes were not statistically significant. In shamoperated rats, neither acute nor chronic morphine treatment significantly altered either right or left ventricular histamine levels. Acute morphine treatment also did not significantly affect the ventricular histamine content at 5 min following coronary artery ligation. However, both right and left ventricular histamine concentrations were found to be significantly lower in chronic morphine-treated rats than in the naive animals when they were subjected to acute myocardial ischaemia. If the hypothesis that histamine release may contribute to the genesis of early ventricular arrhythmias resulting from acute myocardial ischaemia is accepted, the present findings suggest that the previously reported decreased incidence and delayed onset of early ventricular arrhythmias induced by acute left coronary artery ligation in chronic morphine-treated rats may be attributed to the reduced ventricular histamine concentrations.

Ventricular noradrenaline concentrations in naïve and morphine-treated rats subjected to acute myocardial ischaemia

1 Ventricular noradrenaline concentrations in morphine-treated rats subjected to acute left coronary artery ligation were measured by high performance liquid chromatography with electrochemical detection. 2 In naïve rats, acute left coronary artery ligation induced a significant increase in right ventricular noradrenaline concentration at 5 min and significant decreases in left ventricular noradrenaline concentration at 3 and 10 min. 3 Acute morphine treatment did not significantly alter ventricular noradrenaline concentrations in rats subjected to acute coronary artery ligation. 4 Chronic morphine treatment caused significant declines in ventricular noradrenaline concentrations in rats subjected to acute coronary artery ligation. The reductions increased with duration of opiate treatment, and were reversed by opiate withdrawal. 5 These findings indicate that there is an increase in sympathetic activity during acute myocardial ischaemia. It is suggested that chronic morphine treatment may be able to retard this response, and consequently to lessen the occurrence of early ventricular arrhythmias resulting from acute myocardial ischaemia.

Antigen-antibody complex-induced immunosuppression. Effect of F(ab')2 antibodies and protein A

The addition of immune complexes (anti-horse red blood cell (HRC) antibodies plus HRC) to spleen cell cultures activated by lipopolysaccharide (LPS) selectively suppressed the anti-HRC plaque-forming cell (PFC) response, but did not affect the PFC response to sheep red blood cells (SRC). The degree of suppression was directly related to the concentration of immune complexes. F(ab')2 preparations suppressed as efficiently as intact IgG, although the ability of the F(ab')2 preparation to lyse the red cells was abolished. The addition of protein A to the immune complexes (using intact antibodies) did not affect the degree of suppression. The findings suggest that immune complex-induced suppression of polyclonal B cell activation is caused by constant parts of the light or heavy chains of the antibodies other than the Fc part.

Cardiovascular responses to acute myocardial ischaemia in morphine-dependent rats

1. The cardiovascular responses to acute myocardial ischaemia were studied in opiate-dependent animals before and after 2 weeks morphine withdrawal. 2. Rats were treated with morphine sulphate in drinking water for 2, 3 or 5 weeks. The development of morphine tolerance and dependence was verified by the tail-immersion test for analgesia and the naloxone-precipitated withdrawal syndrome, respectively. 3. Acute left coronary artery ligation induced a decrease in blood pressure, a slight increase in heart rate and ventricular tachycardia or fibrillation in anaesthetized naive rats. 4. Chronic morphine treatment did not alter the haemodynamic responses to coronary artery ligation. However, a significantly lowered incidence, and prolonged time of onset, of ventricular arrhythmias was found in 3 and 5 week morphine-treated rats. This phenomenon did not occur in animals receiving morphine for 2 weeks and in a 3 week morphine-treated group which was subsequently withdrawn for 2 weeks. 5. It is suggested that the decreased occurrence of early ventricular arrhythmias resulting from acute myocardial ischaemia in chronic morphine-treated rats may be related to the degree of opiate tolerance and dependence.

Age-related cardiovascular responses of rats to coronary artery ligation

The cardiovascular responses of rats of different ages, ranging from 4-15 weeks (body weight 115-490 g), to acute left coronary artery ligation under pentobarbitone anaesthesia were studied. In older animals, the responses included the occurrence of ventricular tachycardia and/or fibrillation, decrease in blood pressure, and a slight increase in heart rate. On the contrary, younger rats exhibited atrioventricular block followed by ventricular arrest, and decreases in both blood pressure and heart rate. The findings demonstrate the existence of age-related cardiovascular responses to acute myocardial ischaemia in rats, and suggest that 10-15-week-old male Sprague-Dawley rats are suitable experimental animals for producing early ventricular arrhythmias by acute coronary artery ligation.

Morphine reduces vagal-stimulated gastric acid secretion through a central action

The influence of morphine on gastric acid secretion stimulated by 2-deoxy-D-glucose or electrical vagal stimulation was studied in anaesthetised rats with perfused stomachs. It was found that changes in gastric acid output induced by electrical vagal stimulation were not noticeably affected, whereas those evoked by 2-deoxy-D-glucose were significantly suppressed by morphine pretreatment. The depressant effect of the opiate on the acid secretion stimulated by 2-deoxy-D-glucose was abolished by naloxone pretreatment. It is suggested that morphine inhibits vagal-stimulated gastric acid secretion in rats by acting predominantly on opioid receptors in the central nervous system.