BILATERAL NEPHRECTOMY DELAYS GASTRIC EMPTYING OF A LIQUID MEAL IN AWAKE RATS

Figures & data

Figure 1.Effect of bilateral nephrectomy (▪) or sham-operation (□) on the liquid gastric emptying rates in awake rats. The animals were studied 1 day after surgery and sacrificed at 0, 10, 20, 30 or 45 min after liquid meal (1.5 mL of 0.5 mg mL⁻¹ phenol red in 5% glucose solution). Fractional dye recovery was obtained by spectrophotometry from the stomach of sham-operated and nephrectomy groups. Bars represent the gastric emptying (%) mean values while vertical lines means the standard error of mean. n, number of observations. *, P < 0.05 for sham-operation vs. nephrectomy values (ANOVA and Student–Newman–Keuls test).

Table 1. Hemodynamic and Biochemical Parameters Profiles from Sham-Operated and Bilateral Nephrectomized Rats

24 h	Sham-operated	Nephrectomized
Blood volume	8.9 ± 1.1	15.7 ± 0.9 mL/100g*
Urea	47.0 ± 2.8	344.0 ± 33.7 mg/dL*
Creatinine	1.1 ± 0.1	3.6 ± 0.3 mg/dL*
Na^+	139.4 ± 1.98	123.4 ± 7.5 mg/dL
K^+	3.7 ± 0.2	6.4 ± 0.7 mg/dL*
Osmolarity	299.4 ± 1.3	334.0 ± 10.8 mmol/Kg H2O*
Arterial pressure	100.5 ± 4.1	143.3 ± 2.7 mmHg*

After anesthesia, the animals were submitted to a bilateral lumbar incision, followed or not by kidney exeresis. Next day, they were gavage fed with a liquid test meal and sacrificed 20 min later. Following laparotomy, intracardiac blood samples were collected in order to assess some biochemical parameters. Just before gavage, the mean arterial pressure values (AP, in mmHg) were obtained from a continuous recording by a polygraph for 10 min. The plasma volume values (in mL 100 g of body weight⁻¹) were determined by the Evans blue method. The serum osmolarity values (in mOsmKgH₂O⁻¹) were determined by cryoscopy. The urea (nitrogen excretion products) as well as creatinine plasma values (in mg dL⁻¹) were determined by an automatic analyser (Stat Profile Plus9, Nova Medical Corp). Na⁺ and K⁺ plasma values (in mg dL⁻¹) were determined by flame photometry. n, number of observations. *, P < 0.05 for sham-operated vs. nephrectomy groups (ANOVA and Student–Newman–Keuls test).

Figure 2. Correlations between gastric dye retention (%) and blood volume (mL/100 g) values obtained from sham-operated and nephrectomized animals. There is a strong correlation (r² = 0.73) between gastric retention and blood volume in anephric animals (•—•) as indicated by the linear regression equation y = −2.8x + 75.2 while in sham-operated animals (▪—▪) there is no such correlation, according to the regression linear equation y = −1.0x + 73.6, r² = 0.09.