Activation of the Renin‐Angiotensin System in Dogs With Asymptomatic and Mildly Symptomatic Mitral Valvular Insufficiency

Pedersen, Henrik D.; Koch, J.; Poulsen, Knud; Jensen, A. L.; Flagstad, A.

doi:10.1111/j.1939-1676.1995.tb01092.x

Cited by 58 publications

(55 citation statements)

References 12 publications

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“…Intracardiac angiotensin converting enzymes and angiotensin II production are stimulated by diastolic wall stress induced by the low pressure volume overload of mitral regurgitation (Dell'Italia et al, 1995). Also, early activation of the renin-angiotensin system has been demonstrated in dogs with asymptomatic or mildly symptomatic mitral valve insufficiency (Pedersen et al, 1995). Hence, it is possible that the pathological changes of left AV valves in broiler chickens may initiate a sequence of profound hormonal and haemodynamic changes leading to heart failure.…”

Section: Discussionmentioning

confidence: 98%

Left atrio‐ventricular valve degeneration, left ventricular dilation and right ventricular failure: A possible association with pulmonary hypertension and aetiology of ascites in broiler chickens

1998

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The results presented here are based on a collection of heart necropsy data obtained from a large population of ascitic and normal broiler chickens raised at low altitude. The hearts were subjected to gross postmortem evaluation. Generally, gross changes in the cardiac muscle predominantly consisted of various degrees of right and left ventricular enlargement and atrial enlargement, and were observed in all hearts from birds that developed ascites and in some apparently normal chickens. These hearts appeared flaccid, had a thin ventricular muscle wall, and lacked the normal tone of healthy heart muscle. Ventricular enlargement (mostly dilation) and AV valve degeneration (endocardiosis) were observed as early as 7 to 10 days of age and throughout the remaining growth period in broilers with or without ascites. The hearts from 264 ascitic and 255 apparently normal commercial broilers were used for quantitative analysis, with emphasis on dilatory changes of the ventriculi and detailed evaluation of the atrio-ventricular (AV) valves. The lesions of the AV apparatus and the degree of dilation of the ventriculi were graded according to a priori established standards, and categorized as mild, moderate or severe. Severe or moderate dilation of both the right and left ventricle were observed more frequently (P < 0.001) in ascitic birds than in normal birds. Of hearts from apparently normal birds, 34 and 61% had grossly normal right and left ventricle, respectively. Overall, 30% of ascitic birds had a grossly normal left ventricle, but some degree of right ventricular dilation was found in all ascitic birds. Prominent endocardiosis was a common feature in a majority of hearts from ascitic birds and in some apparently normal birds. Endocardiosis of the left AV valves was observed considerably more frequently (P < 0.001) than of right AV valves. Most severe lesions were found on left AV valves, and consisted of nodules or coalescing formations associated with annulus, valve cusps, chordae tendineae, and sometimes spread to the mural endocardium in the vicinity of the valve apparatus. Frequently the cusps appeared thickened and rigid, and had rolled edges. Chordae tendineae were frequently thickened, and sometimes ruptured. These severe left AV valve lesions were found most frequently (P < 0.001) in the hearts from ascitic birds (52%) in comparison to apparently normal birds (18%). The right AV valve lesions were mainly in the form of small nodules found around the orifice, and less frequently seen on the muscular leaflets of the right valve. Only in a few instances the nodules were larger, ranging from 1 to 3 mm in diameter. The severity of gross lesions on the left AV valve were indicative of stenosis and/or insufficiency of the valve apparatus. A hypothesis that left atrio-ventricular valve degeneration and left ventricular dilation should be considered as a possible aetiologic association with pulmonary hypertension, right ventricular failure, and ascites in broiler chickens is presented and discussed.

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Section: Discussionmentioning

confidence: 98%

Left atrio‐ventricular valve degeneration, left ventricular dilation and right ventricular failure: A possible association with pulmonary hypertension and aetiology of ascites in broiler chickens

1998

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“…It is well accepted that plasma renin and/or Ang II level is elevated in CHF due to rapid pacing [27], cardiac infarction [28,29], mitral valvular diseases [30], or human congestive heart failure [31]. On the other hand, Iwanaga et al [32] reported that the plasma Ang II level was within a normal range in salt-sensitive hypertension-induced heart failure, which indicates that salt-induced heart failure may not have high RAS activity.…”

Section: Discussionmentioning

confidence: 95%

Endogenous angiotensin II has fewer effects but neuronal nitric oxide synthase has excitatory effects on renal sympathetic nerve activity in salt-sensitive hypertension-induced heart failure

et al. 2009

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The effects of endogenous angiotensin II (Ang II) and neuronal nitric oxide synthase (nNOS) on tonic sympathetic activity were studied in salt-sensitive hypertension-induced heart failure. Dahl salt-sensitive rats were fed 8% NaCl diet for 9 weeks to induce chronic heart failure (CHF-DSS). The effects of intravenous administration of a selective nNOS inhibitor, S-methyl-L: -thiocitrulline (SMTC), and an Ang II type 1-receptor blocker, losartan, on renal sympathetic nerve activity (RSNA) were examined in chronically instrumented conscious rats. Baroreceptor (baro)-unloaded RSNA was obtained by decreasing arterial pressure with caval occlusion to determine tonic RSNA. SMTC significantly decreased baro-unloaded RSNA, and subsequent losartan recovered baro-unloaded RSNA to the control level in CHF-DSS rats. To compare the effects of the inhibitors between low- and high-activity states of the renin-angiotensin system (RAS), Sprague-Dawley rats were fed low (0.04%)- or high (8%)-salt diets. A significant difference was found in the effects of SMTC and/or losartan on RSNA between the high- and low-RAS states, which suggested that there is a difference in the effect of endogenous Ang II on RSNA between salt-induced and other-type heart failure. To examine the effects of heart failure on brain-tissue nNOS activity, we measured the activities of the diencephalon in heart-failure rats. Heart failure significantly suppressed diencephalon nNOS activity, which was significantly different from the results in salt-sensitive hypertension without heart failure. These results suggest that endogenous Ang II has fewer effects, but nNOS has excitatory effects on tonic RSNA in salt-sensitive hypertension-induced heart failure.

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“…Its contribution to the development of hypertension (HT) and congestive heart failure (CHF) has long been recognized (Kunita et al, 1976;Nicholls et al, 1993;Pedersen et al, 1995;Roche et al, 2002). Results from our previous research (Mochel et al, 2013) have shown that variables of the renin cascade and BP oscillate with a 24-h periodicity in dogs fed a regular diet at 07:00 h. In this earlier study, dietary sodium was found to have an influence on the chronobiology of RA and urinary aldosterone, indicating that varying feeding schedules could also impact the chronobiology of the renin cascade.…”

Section: Discussionmentioning

confidence: 99%

Influence of feeding schedules on the chronobiology of renin activity, urinary electrolytes and blood pressure in dogs

Mochel

Fink

Bon

et al. 2014

Chronobiology International

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The contribution of the renin-angiotensin-aldosterone system (RAAS) to the development of congestive heart failure (CHF) and hypertension (HT) has long been recognized. Medications that are commonly used in the course of CHF and HT are most often given with morning food for the sake of convenience and therapeutic compliance. However, biological rhythms and their responsiveness to environmental clues such as food intake may noticeably impact the effectiveness of drugs used in the management of cardiovascular disorders. Only sparse information about the effect of feeding schedules on the biology of the RAAS and blood pressure (BP) is presently available. Two studies were designed to explore the chronobiology of renin activity (RA), BP, renal sodium (UNa,fe) and potassium (UK,fe) handling in relation to meal timing in dogs. In a first experiment (Study a), blood and urinary samples for measurement of RA, UNa,fe and UK,fe were drawn from 18 healthy beagle dogs fed a normal-sodium diet at either 07:00, 13:00 or 19:00 h. In a second experiment (Study b), BP was recorded continuously from six healthy, telemetered beagle dogs fed a similar diet at 07:00, or 19:00 h. Data were collected throughout 24-h time periods, and analyzed by means of nonlinear mixed-effects models. Differences between the geometric means of early versus late time after feeding observations were further compared using parametric statistics. In agreement with our previous investigations, the results indicate that RA, UNa,fe, UK,fe, systolic, and diastolic BP oscillate with a circadian periodicity in dogs fed a regular diet at 07:00 h. A cosine model with a fixed 24-h period was found to fit the variations of RA, UK,fe and BP well, whereas cyclic changes in UNa,fe were best characterized by means of a combined cosine and surge model, reflecting a postprandial sodium excretion followed by a monotonous decay. Our data show that feeding time has a marked influence on the chronobiology of the renin cascade, urinary electrolytes, and BP. Introducing a 6- or 12-h delay in the dogs' feeding schedule caused a shift of similar magnitude (05:06 and 12:32 h for Studies a and b, respectively) in the rhythm of these biomarkers. In all study groups, RA and BP exhibited a marked fall just after food intake. The drop in RA is consistent with sodium and water-induced body fluid expansion, while the reduction of BP could be related to the decreased activity of renin and the secretion of vasodilatory gut peptides. An approximately 1.5-fold (1.2-1.6-fold) change between the average early and late time after feeding observations was found for RA (p < 0.0001), UNa,fe (p < 0.01) and UK,fe (p < 0.05). Postprandial variations in BP, albeit small (ca. 10 mmHg), were statistically significant (p < 0.01) and supported by the model-based analysis. In conclusion, the timing of food intake appears to be pivotal to the circadian organization of the renin cascade and BP. This synchronizing effect could be mediated by feeding-related signals, such as dietary sodium, capable of entrain...

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Activation of the Renin‐Angiotensin System in Dogs With Asymptomatic and Mildly Symptomatic Mitral Valvular Insufficiency

Cited by 58 publications

References 12 publications

Left atrio‐ventricular valve degeneration, left ventricular dilation and right ventricular failure: A possible association with pulmonary hypertension and aetiology of ascites in broiler chickens

Left atrio‐ventricular valve degeneration, left ventricular dilation and right ventricular failure: A possible association with pulmonary hypertension and aetiology of ascites in broiler chickens

Endogenous angiotensin II has fewer effects but neuronal nitric oxide synthase has excitatory effects on renal sympathetic nerve activity in salt-sensitive hypertension-induced heart failure

Influence of feeding schedules on the chronobiology of renin activity, urinary electrolytes and blood pressure in dogs

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