spirapril and Disease-Models--Animal

Pharmacological and genetic interference with the renin-angiotensin system (RAS) seems to alter voluntary ethanol consumption. However, understanding the influence of the RAS on ethanol dependence and its treatment requires modeling the neuroadaptations that occur with prolonged exposure to ethanol. Increased ethanol consumption was induced in rats through repeated cycles of intoxication and withdrawal. Expression of angiotensinogen, angiotensin-converting enzyme, and the angiotensin II receptor, AT1a, was examined by quantitative reverse transcription polymerase chain reaction. Increased ethanol consumption after a history of dependence was associated with increased angiotensinogen expression in medial prefrontal cortex but not in nucleus accumbens or amygdala. Increased angiotensinogen expression also demonstrates that the astroglia is an integral part of the plasticity underlying the development of dependence. The effects of low central RAS activity on increased ethanol consumption were investigated using either spirapril, a blood-brain barrier-penetrating inhibitor of angiotensin-converting enzyme, or transgenic rats (TGR(ASrAOGEN)680) with reduced central angiotensinogen expression. Spirapril reduced ethanol intake in dependent rats compared to controls. After induction of dependence, TGR(ASrAOGEN)680 rats had increased ethanol consumption but to a lesser degree than Wistar rats with the same history of dependence. These data suggest that the central RAS is sensitized in its modulatory control of ethanol consumption in the dependent state, but pharmacological or genetic blockade of the system appears to be insufficient to halt the progression of dependence.

Topics: Adaptation, Physiological; Alcoholism; Angiotensin II; Angiotensin II Type 1 Receptor Blockers; Angiotensin-Converting Enzyme Inhibitors; Angiotensinogen; Animals; Animals, Genetically Modified; Central Nervous System; Disease Models, Animal; Enalapril; Ethanol; Humans; Neuronal Plasticity; Rats; Rats, Wistar; Receptors, Angiotensin; Renin-Angiotensin System; RNA, Antisense

Topics: Adaptation, Physiological; Angiotensin-Converting Enzyme Inhibitors; Animals; Disease Models, Animal; Enalapril; Myocardial Ischemia; Rats; Severity of Illness Index; Tachycardia

Blunted cardiac responses to sympathetic and vagal activation are key features of heart failure. Since the modulation of drug effects by a selective autonomic dysfunction is little known, we developed an acute rabbit model imitating these defects. Anesthetized rabbits were subject to cervical vagotomy and propranolol (1 mg/kg i.v.) pretreatment, thus eliminating vagally and sympathetically mediated cardiac responses, while maintaining the responsiveness of the peripheral circulation to these reflexes ("V-B" animals). Responses to drugs were altered in V-B compared with normal animals: Ouabain (5-50 micrograms/kg) increased myocardial contractile force more and milrinone (30-300 micrograms/kg) less, yet it increased the heart rate more; the reflex tachycardia to nitroprusside (1-10 micrograms/kg/min) was blunted and spirapril (0.1 and 1 mg/kg, all i.v.) decreased the central venous pressure only in V-B animals. Several drug effects were thus strongly modulated by autonomic dysfunction and responses of V-B animals were closer to those of heart failure patients than the responses of the normal animals, especially for milrinone.

Topics: Animals; Autonomic Nervous System; Cardiovascular Agents; Disease Models, Animal; Enalapril; Heart Failure; Heart Rate; Milrinone; Myocardial Contraction; Nitroprusside; Ouabain; Propranolol; Pyridones; Rabbits; Vagotomy; Vasodilator Agents

The aim was to compare the effects of two novel angiotensin converting enzyme (ACE) inhibitors, spirapril and zofenopril, on cardiac remodelling in rats with congestive heart failure after myocardial infarction. Spirapril contains no sulphydryl group, whereas zofenopril is a sulphydryl containing ACE inhibitor.. Experimental myocardial infarction was induced by ligation of the left coronary artery. Sham operated animals served as controls. Treatment with spirapril (2-2.5 mg.kg-1.d-1) or zofenopril (12-15 mg.kg-1.d-1) added to the drinking water was started immediately after myocardial infarction or sham operation and continued for six weeks. After the treatment period, all rats were killed. The heart was rapidly removed and perfused as described by Langendorff. Heart rate and left ventricular pressure were measured both at baseline and during stimulation with isoprenaline (6 nM). Heart and lung weights were determined.. Normotensive male Wistar rats (220-240 g) were used.. Experimental myocardial infarction considerably increased left ventricular cavity volume. Chronic treatment with either spirapril or zofenopril significantly attenuated this increase in volume. In infarcted rats, the increase in total heart and lung weight was also significantly reduced by chronic treatment with spirapril and zofenopril, indicating that these compounds reduce cardiac mass and pulmonary congestion in congestive heart failure due to myocardial infarction. There were no significant differences between treatment with spirapril and zofenopril. In the isolated and perfused rat heart, myocardial infarction significantly decreased both heart rate and left ventricular pressure. Converting enzyme inhibition only affected heart rate. Heart rate was significantly higher in infarcted animals treated with spirapril and zofenopril than in untreated infarcted animals.. Both spirapril and zofenopril attenuated ventricular enlargement and cardiac hypertrophy in rats with congestive heart failure after myocardial infarction when treatment was started in the acute phase of myocardial infarction. No additional role could be attributed to the sulphydryl moiety of zofenopril. It is also suggested that these two ACE inhibitors modify cardiac sympathetic activity in rats with congestive heart failure, but more studies are needed to confirm these findings.

Topics: Angiotensin-Converting Enzyme Inhibitors; Animals; Captopril; Disease Models, Animal; Enalapril; Heart; Heart Rate; Isoproterenol; Male; Myocardial Infarction; Myocardium; Rats; Rats, Inbred Strains