The isolated working heart model in infarcted rat hearts.

Congestive heart failure (CHF) is one of the most common causes of death in western countries. The aim of this study was to establish and validate the working heart model in rat hearts with CHF. In the rat model the animals show parameters and symptoms that can be extrapolated to the clinical situation of patients with end-stage heart failure.

A model of chronic heart failure in spontaneous hypertensive rats (SHR).

Common models of chronic heart failure (CHF) do not always result in parameters and symptoms that can be extrapolated to the clinical situation of patients with end-stage heart failure. The aim of this study was to establish and validate a new model of CHF in the rat. CHF was induced in Wistar Kyoto (WKY/NHsd) and spontaneously hypertensive (SHR/NHsd) rats by creating a permanent (8-week) occlusion of the left coronary artery 2 mm distal to the origin from the aorta by a modified technique.

Ischemic preconditioning and infarct mass: the effect of hypercholesterolemia and endothelial dysfunction.

In an experimental model of atherosclerosis we investigated whether rabbits fed an atherogenic diet (0.25% cholesterol, 3% coconut oil) develop endothelial dysfunction accompanied with increased infarct mass compared to normal fed rabbits and, whether hypercholesterolemia would interfere with the beneficial outcome of ischemic preconditioning observed in normal rabbits. After four weeks on either a normal or an atherogenic diet, New Zealand White rabbits (n=7 in each group) were subjected to 30 min of myocardial ischemia by occlusion of a branch of the left anterior descending coronary artery (LAD) followed by 2 hours of reperfusion (infarct studies).

Ramiprilat prevents the development of acute coronary endothelial dysfunction in the dog.

We investigated the effect of an infusion of ramiprilat on the development of coronary endothelial dysfunction. In anesthetized dogs, the endothelium-dependent vasodilators acetylcholine (ACh, 5 and 10 microg x min(-1) for 1 min) and serotonin (5-HT, 50 and 100 microg x min(-1) for 1 min) and the endothelium-independent vasodilator nitroglycerin (NTG, 50 and 100 microg x min(-1) for 1 min) were given intracoronarily (i.c.

Late treatment with ramipril increases survival in old spontaneously hypertensive rats.

Spontaneously hypertensive rats (SHR) begin to die from cardiovascular complications at approximately 15 months of age. We tested whether chronic ACE-inhibitor treatment would extend the lifespan of such old animals. We also studied cardiac hypertrophy and function, endothelial function and expression, and activity of NO synthase (eNOS).

Myocardial angiotensin receptor type 1 gene expression in a rat model of cardiac volume overload.

To investigate the regulation of the angiotensin receptor type 1 (AT1) in different organs in cardiac volume overload, we measured AT1 mRNA content in the atria, left and right ventricle, kidney and liver of rats with an aortocaval shunt, produced by infrarenal aortocaval puncture 4 weeks earlier. For angiotensin receptor mRNA quantitation a novel quantitative PCR procedure based on liquid phase hybridization was used that allowed the determination of absolute AT1 mRNA copy numbers and its comparison in different organs. Glyceraldehydephosphate dehydrogenase (GAPDH) mRNA was measured by RT-PCR to control externally equal mRNA content and quality of RNA extraction in shunt animals and controls.

Cardiotonic activity of the water soluble forskolin derivative 8,13-epoxy-6 beta-(piperidinoacetoxy)- 1 alpha, 7 beta, 9 alpha-trihydroxy-labd- 14en-11-one.

8,13-Epoxy-6 beta-(piperidinoacetoxy)-1 alpha,7 beta, 9 alpha-trihydroxy-labd -14en-11-one (HL 706, CAS 114376-11-3) is a water soluble derivative of forskolin with positive inotropic and vasodilating properties. In both in vitro and in vivo preparations, it exhibited significant positive inotropic activity with concomitant increase in heart rate and decrease in mean blood pressure. Though its potency is lower than that of forskolin, its duration of action is more prolonged.

Bradykinin-mediated metabolic effects in isolated perfused rat hearts.

Bradykinin perfusion (BK 1 x 10(-12) to 1 x 10(-8) mol/l) of isolated working rat hearts with postischemic reperfusion arrhythmias induced a reduction of the incidence as well as duration of ventricular fibrillation, improvement of cardiodynamics via increased left ventricular pressure, contractility, and coronary flow without changes in heart rate. These beneficial effects were accompanied by reduced activities of the cytosolic enzymes lactate dehydrogenase and creatine kinase as well as lactate output. In the myocardial tissue lactate content was reduced and the energy rich phosphates increased compared to saline perfused control hearts.

Intracardiac generation of angiotensin and its physiologic role.

The emerging recognition of the existence and potential biological significance of local tissue renin-angiotensin systems in a number of organs has fostered interest in a possible intrinsic cardiac renin-angiotensin system. Evidence for such a system was first provided by biochemical measurements of components of the renin-angiotensin system in cardiac tissue. It has recently been demonstrated that the genes coding for renin and angiotensinogen are expressed in all regions of the heart, an essential prerequisite for the postulated intracardiac biosynthesis of these proteins.

Chemical and biologic characteristics of roxatidine acetate.

Roxatidine acetate is a specific and competitive H2-receptor antagonist, as shown in isolated rabbit gastric glands or guinea pig atria preparations. The antisecretory effect of roxatidine acetate is mediated by its main metabolite, roxatidine. In the rat, roxatidine acetate was equipotent after intraduodenal and intraperitoneal administration, indicating excellent bioavailability.

Tissue renin-angiotensin systems: focus on the heart.

Recent findings support the existence of independently functioning, local renin-angiotensin systems in a number of tissues. The clinical importance that inhibitors of the renin-angiotensin system have gained in the treatment of hypertension and cardiac failure, as well as molecular biology data, suggest that a functional, tissue renin-angiotensin system is present in the heart. Using several experimental approaches we present evidence to support the existence and the possible physiopathological relevance of such a cardiac renin-angiotensin system.

Hypotensive action of an intra-nasally applied angiotensin II-antagonist.

Intranasal administration of the specific angiotensin II-antagonist (1-NSuc-5-Val-8-Phg) A II was investigated in anaesthetized rats with different forms of experimentally elevated blood pressure. Renin- or angiotensin II-induced blood pressure increases were markedly reversed by the angiotensin II-antagonist applied intra-nasally. In rats with acute accelerated elevation of blood pressure the analogue induced also a significant decrease.

Blood pressure response to central and peripheral injection of angiotensin II and 8-C-phenylglycine analogue of angiotensin II in rats with experimental hypertension.

1. We have compared the effect of central and peripheral administration of angiotensin II and (1-succinamoly-5-valine-8-phenylglycine)angiotensin II on blood pressure of male conscious unrestrained rats with normal blood pressure, and with spontaneous hypertension or chronic renal hypertension. 2.

1,8-disubstituted analogues of (Ile5) and (Val5)angiotensin II: difference in potency and specificity of angiotensin II-antagonistic activity.

Depending on the species, position 5 in angiotensin II is occupied by isoleucine or valine. 1,8-disubstituted analogues of [Ile5]angiotensin II show distinct differences from the corresponding [Val5]angiotensin II analogues in the potency and specificity of their inhibitory action. The syntheses of new analogues are described.

Comparative pharmacology of new specific angiotensin antagonists.

1. The angiotensin II antagonism by newly synthesized 8-C-phenylglycine analogues of [5-isoleucine]angiotensin II in different preparations was investigated in vitro and in vivo. 2.