Chollada Buranakarl

L-carnitine ameliorates doxorubicin-induced nephrotic syndrome in rats

Aim:  Effects of L‐carnitine on nephrotoxicity and oxidative stress induced by doxorubicin (DOX) in rats were investigated.

Effects of acute heat stress on changes in the rate of liquid flow from the rumen and turnover of body water of swamp buffalo

During 5 h of acute heat exposure (41 °C), there were increases in the heart rate from 43±2 (S.E.) to 51 ± 1 beats/min, respiratory rate from 26±4 to 86± 16 breaths/min and rectal temperature from 38·5 ± 0·1 °C to 39·7 ± 0·2 °C. The flow rate of liquid from the rumen and body water turnover significantly increased while biological half life of chromium-51 ethylenediaminetetra-acetate in the rumen and tritiated water decreased from 12·9 ± 2·5 and 87·7 ± 6·8 h to 9·3 ± 2·0 and 49·2 ± 5·7 h respectively. An increase in blood volume during acute heat stress occurred with an increase of both plasma and cell volume. An elevation of plasma water coincided with an increase in plasma protein and glucose. There is evidence that the increase in plasma water during heat exposure came from extravascular tissue space and/or from the digestive tract.

Relationships Between Degree of Azotaemia and Blood Pressure, Urinary Protein:Creatinine Ratio and Fractional Excretion of Electrolytes in Dogs with Renal Azotaemia

Blood pressure (BP) was measured in 31 renal azotaemic dogs by oscillometric measurement at the posterior tibia artery, and urine and blood samples were collected. Haematology, blood chemistry and urinalysis were performed and urinary protein:creatinine ratio (UPC) and fractional excretions of electrolytes (FEe) were calculated. The results showed that only 19% of dogs with renal azotaemia were hypertensive, whereas almost all of them had high urinary protein and electrolyte excretions. There was no association between BP, UPC and FEe. A positive correlation was found between all pairs of electrolyte fractional excretions. When the severity of renal impairment was observed using plasma creatinine concentration, neither BP nor UPC was correlated. Only the FEe was associated with the degree of azotaemia. The results suggest that dogs with renal azotaemia do not necessarily have hypertension. The fractional urinary excretion of electrolytes may be a good indicator for severity of renal dysfunction in azotaemic dogs.

Relationships between oxidative stress markers and red blood cell characteristics in renal azotemic dogs

Oxidative stress parameters and erythrocyte characteristics were studied in 15 normal healthy dogs and 33 renal azotaemic dogs from Small Animal Hospital, Faculty of Veterinary Science, Chulalongkorn University. Dogs with renal azotaemia had reduced mean corpuscular volume (MCV) (P<0.01), packed cell volume (PCV) (P<0.001) and increased mean corpuscular hemoglobin concentration (MCHC) (P<0.001). The relationship was found between degree of azotaemia and MCV, PCV and MCHC. Dogs with severe renal azotaemia had higher intraerythrocytic sodium contents (RBC-Na) (P<0.05). The red blood cell catalase activity and glutathione and plasma malondialdehyde were unaltered while urinary malondialdehyde-creatinine ratio (U-MDA/Cr) increased significantly (P<0.001). The U-MDA/Cr was correlated significantly with plasma creatinine concentration (P<0.05), urinary protein-creatinine ratio (P<0.05) and fractional excretion of sodium (P<0.001). The results suggest some changes in RBC characteristics and urine oxidative stress marker in renal azotaemic dogs. Moreover, the U-MDA/Cr is a sensitive biochemical parameter which increased along with degree of renal dysfunction.

Decreased sympathetic tone after short-term treatment with enalapril in dogs with mild chronic mitral valve disease.

Heart rate variability (HRV) and echocardiography were performed in 14 dogs with mitral regurgitation (MR) before and after 14 days of 0.5mg/kg/day of enalapril treatment. All dogs were in heart failure stages B1 and B2. After enalapril treatment, left ventricular end diastolic diameter (LVEDd), left ventricular end diastolic diameter normalized for body weight (LVEDdN) and percent mitral regurgitant jet decreased (P<0.05). The diastolic blood pressure decreased (P<0.05). Increased time domain parameters of HRV were found. For frequency domain analysis, the total frequency (TF) increased significantly (P<0.05). The normalized low frequency (LF norm) decreased while normalized high frequency (HF norm) increased causing significant reduction in LF/HF (P<0.05). Before enalapril treatment, LF was correlated with end diastolic volume (EDV) (P<0.01) and LVEDd (P<0.05). In conclusion, MR dogs receiving enalapril treatment for 14 days had increased cardiac parasympathetic tone while sympathetic tone was suppressed. The decreased sympathetic activity corresponded to the reduction in cardiac preload and afterload.

Comparison of dipyridamole and fosinopril on renal progression in nephrectomized rats

SUMMARY:   There is evidence to suggest that antiplatelet aggregation and inhibition of angiotensin converting enzyme will attenuate the progression of renal disease. In the present study, dipyridamole (DPM; 30 mg/kg per day, p.o.) or fosinopril (FOS; 20 mg/kg per day, p.o.) was given to rats for 5 weeks starting immediately after renal mass reduction (right uninephrectomy and ligation of approximately two‐thirds of the blood supply to the left kidney). Renal mass reduction caused increased mean arterial blood pressure, reduced effective renal plasma flow (ERPF) and glomerular filtration rate (GFR), azotemia and proteinuria. Neither proteinuria nor hypertension was affected by DPM, although renal function improved markedly. Rats receiving FOS showed normalization of blood pressure with a significant increase in both ERPF and GFR, along with a lower degree of proteinuria. A histological examination of the remnant kidney detected the presence of vasodilation with a lower degree of podocyte swelling in both treatment groups, with a remarkable effect in the FOS group. These data indicate that both FOS and DPM attenuate the progression of glomerular disease associated with renal mass reduction in rats. However, FOS was more beneficial than DPM because it reduced proteinuria and lowered blood pressure.

Effects of exogenous urea infusion on glucose metabolism in acute heat stressed swamp buffaloes (Bubalus bubalis)

The effects of intravenous urea infusion on glucose turnover, glucose carbon recycling, glucose pool size and glucose clearance were studied in buffaloes kept in either normal ambient temperature or acute heat exposure. Heat stressed animals showed increases in glucose turnover rate, plasma glucose concentration and glucose clearance but decreased glucose carbon recycling. A marked reduction of glucose turnover and glucose clearance associated with increased plasma glucose concentration in heat stressed animals after urea infusion reflects under-utilization of this compound. Mechanisms involved in glucose metabolism during urea infusion in buffaloes are discussed.

Effects of Fosinopril on Renal Function, Baroreflex Response and Noradrenaline Pressor Response in Conscious Normotensive Dogs

The blood pressure, renal function, baroreflex response of heart rate and noradrenaline (norepinephrine) pressor response were determined in conscious, normotensive, sodium-replete dogs that had received fosinopril. Oral administration of fosinopril at a dose of 1 mg/kg per day for 5 days decreased the systolic arterial pressure from 147.1±3 to 131.8±4.3 mmHg (p<0.05) and the mean arterial pressure from 99.7±3.9 to 87.5±2.8 mmHg (p<0.05), while heart rate was unchanged. A study of the noradrenaline pressor response showed a tendency to alleviate the increased MAP by fosinopril treatment, although this was not significant. There were no significant changes in the sensitivity of the baroreflex response in HR, although the setpoint was reduced. After 7 days of fosinopril treatment, the glomerular filtration rate had increased by 18.5% (p<0.05). The effective renal plasma flow tended to increase, leaving the filtration fraction unchanged. The renal vascular resistance was reduced by 11.3% (p<0.05). Fosinopril caused a significant 41.5% increase in urinary excretion of Na+ (p<0.05), along with an elevation of urinary excretion of K+ and Cl–. It is concluded that fosinopril can lower the blood pressure, reduce the noradrenaline pressor response and lower the cardiac baroreflex setpoint to noradrenaline. Oral administration of fosinopril for 7 days affects both the renal haemodynamics and electrolyte excretions in conscious, normotensive, sodium-replete dogs.

Changes in renal functions during β-blocker carazolol administration in acute heat-stressed pigs

Abstract During 2 h of acute heat exposure in pigs (36:27 °C, dry bulb: wet bulb temperature), the rectal temperature increased from 40·5 to 42·3 °C, the heart rate (HR) increased from 122 ± 7 to 176 ± 16 beats/min, and the respiratory rate (RR) increased from 48 ± 9 to 196 ± 11 breaths/min. There were no significant changes in the mean arterial blood pressure and renal haemodynamics in heat-stressed pigs. Plasma concentration of Cl− significantly increased while plasma Na+ and K+ did not change. In the second hour of heat exposure, the rate of urine flow was unchanged while urinary pH and fractional and urinary excretion of K+ significantly increased. The intravenous injection of β-blocker carazolol (0·1 mg/kg) in heat-stressed animals slightly affected RR, while there was a marked reduction of HR. The glomerular filtration rate and renal blood flow slightly increased whereas fractional excretion of K+, plasma Cl− concentrations, and urinary pH markedly decreased after carazolol administration. These findings suggest that in heat-stressed animals, carazolol influences the renal electrolyte transport activities by directly altering the acid-base balance mechanism.

Oxidative stress and intraerythrocytic concentrations of sodium and potassium in diabetic dogs

Oxidative stress parameters; thiobarbituric acid reaction substances (RBC-TBARS), catalase (RBC-CAT) and reduced glutathione (RBC-GSH)) and the intraerythrocytic concentrations of electrolytes; sodium and potassium (RBC-Na and RBC-K) were determined in 18 well- controlled (WC) and 22 poorly-controlled diabetic mellitus (DM). Dogs with DM had significant higher blood glucose concentration (P < 0.001), haemoglobin A1c (P < 0.01) and fructosamine (P < 0.001) compared to normal healthy dogs (n = 19). Diabetic dogs in both groups had higher RBC-CAT (P < 0.05) while RBC-TBARS were higher significantly only in poorly-controlled DM group (P < 0.05). The RBC-K was significantly higher in both DM groups (P < 0.001). No changes in RBC-GSH and RBC-Na were found between DM and control healthy dogs. By linear regression analysis, the relationship were found between degree of diabetic mellitus and RBC-CAT, RBC-TBARS, RBC-Na and RBC-K. The relationship was also found between oxidative stress parameters and intraerythrocytic K+. The results suggest that in diabetic dogs, oxidative stress occurs which related to the severity of disease and may affect potassium homeostasis.