The Effect of Angiotensin‐Converting Enzyme Inhibitors of Left Atrial Pressure in Dogs with Mitral Valve Regurgitation

Background: Despite many epidemiological reports concerning the efficacy of angiotensin‐converting enzyme (ACE) inhibitors in dogs with mitral regurgitation (MR), the hemodynamic effects of ACE inhibitor administration have not been fully evaluated. Objectives: To document left atrial pressure (LAP) in dogs with MR administered ACE inhibitors, in order to obtain interesting information about daily LAP changes with administration of ACE inhibitors. Animals: Five healthy Beagle dogs weighing 9.8 to 14.2 kg (2 males and 3 females; aged 2 years). Methods: Experimental, crossover, and interventional study. Chordae tendineae rupture was induced, and a radiotelemetry transmitter catheter was inserted into the left atrium. LAP was recorded for 72 consecutive hours during which each of 3 ACE inhibitors—enalapril (0.5 mg/kg/d), temocapril (0.1 mg/kg/d), and alacepril (3.0 mg/kg/d)—were administered in a crossover study. Results: Averaged diurnal LAP was significantly, but slightly reduced by alacepril (P= .03, 19.03 ± 3.01–18.24 ± 3.07 mmHg). The nightly drops in LAP caused by alacepril and enalapril were significantly higher than the daily drops (P= .03, ?0.98 ± 0.19 to ?0.07 ± 0.25 mmHg, and P= .03, ?0.54 ± 0.21–0.02 ± 0.17 mmHg, respectively), despite the fact that the oral administrations were given in the morning. Systolic blood pressure (122.7 ± 14.4–117.4 ± 13.1 mmHg, P= .04) and systemic vascular resistance (5800 ± 2685–5144 ± 2077 dyne × s/cm⁵, P= .03) were decreased by ACE inhibitors. Conclusions and Clinical Importance: ACE inhibitors decrease LAP minimally, despite reductions in left ventricular afterload. ACE inhibitors should not be used to decrease LAP.     

Preliminary immunohistochemical study of natriuretic peptide receptor localization in canine and feline heart

We examined the immunohistochemical distributions of natriuretic peptide receptor (NPR)-A, -B and -C that bind with natriuretic peptide hormones A, B and C in four healthy crossbreed young canine and feline cardiac tissues using specific antibodies against human antigens. Cross-immunoreactivities between antigens and antibodies were confirmed using western blot analysis. NPR-A and -C were expressed more strongly in dogs than cats. In both species, these expressions were stronger in the atria than the ventricles, with stronger expression in the left ventricles than the right. NPR-B was largely very weekly or undetected. In canine and feline cardiac tissues, the expressional distribution of NPR-A, -B, and -C closely matched with that of atrial natriuretic peptide, brain natriuretic peptide, and C-type natriuretic peptide as the ligands for corresponding receptors.     

Method of extracting organic acid from flooded soil

Investigations on the extraction and determination of organic acids in flooded soil have been reported by TAKAI (1) and TAKIJIMA (2). TAKAI applied water to extract acids from soil and determined them by BULLEN's method (3). However, TAKIJIMA reported that organic acid could not be completely extracted by TAKAI's procedure, especially in soil with a high organic matter content such as muck and peaty soils, and proposed an extraction procedure with 0.5 N sulfuric acid. He also discussed the absorption of acids by soil.     

On the interlamellar complex between montmorillonite and organic substance in certain soil

KODAMA and SCHNITZER (1) have shown that organic substance of the fluvic acid fraction separated from a podzol soil could penetrate into the interlamellar region of montmorillonite. But the natural occurence of such a complex has not been observed yet (2).     

Energy requirement of laying japanese quail

1. Two feeding experiments were conducted to determine the meta‐bolisable energy (ME) requirement of laying Japanese quail. Birds were fed to provide 5.5 g protein and 167, 209, 251 or 293 kJ ME/d.

2. As ME intake increased from 167 to 293 kJ egg production increased.

3. Quadratic relationships between ME intake and egg production, ME intake and egg weight, and ME intake and egg mass (g egg/ bird d) were derived and used to determine the energy required for an acceptable production rate.

4. To maintain a production of 8.3 g egg/bird d (90 eggs/100 bird d with a mean weight of 9.3 g) required 260 kJ ME/bird d.     

Daily Rhythms of Left Atrial Pressure in Beagle Dogs with Mitral Valve Regurgitation

Background: Mitral valve regurgitation (MR) causes increased left atrial pressure (LAP) and is associated with occurrence of clinical signs. It will be useful to understand diurnal variations of LAP for the management of MR.
Hypothesis: Circulatory parameters and diurnal rhythm are linked to clinical signs in cardiac diseases. LAP also exhibits a diurnal rhythm in dogs with MR.
Animals: Five healthy Beagle dogs weighing 9.8–12.8 kg (3 males and 2 females; aged 2 years) were used.
Methods: A radiotelemetry system for continuous measurement of LAP was used in this study. Rupture of the chordae tendineae was experimentally induced via left atriotomy, and a transmitter catheter was inserted into the left atrium. The body of the transmitter was implanted SC. After clinical condition was stabilized, the severity of MR was evaluated by echocardiography, and LAP was recorded for 72 consecutive hours for the analysis of diurnal variation.
Results: Abrupt increases in LAP, which averaged 16.7 mmHg, were observed at feeding periods. In contrast, strong diurnal LAP variations were found, with a significant but slight increase in daytime LAP compared with nighttime LAP.
Conclusions and Clinical Importance: Diurnal LAP is characterized by a slight but significant nocturnal decrease and abrupt increases in response to excitation. The latter seemed to be more important considering the relationship with clinical manifestations. The clinical relevance of exercise restriction in the management of MR was acknowledged.