Effects of hypoxia on renal function in carp

The influence of hypoxia upon renal function in fish has been studied, and investigation of blood properties and cardiac function was conducted to gain a better understanding of renal response to hypoxia in fresh water teleosts. Hypoxic conditions were induced by allowing the fish to consume available dissolved oxygen (DO) in a 10 l experimental tank. When the DO level fell to about 5% of oxygen saturation after several hour stress, carp had lost balance. As water flow and aeration to the tank were established, carp recovered their balance within several minutes. Glomerular filtration rate (GFR) and urine flow decreased with increased urinary concentrations of bi-components, except protein, in the course of hypoxia. Decreases in blood pH and plasma prostaglandin E sub(2), and increase in Ht, plasma K super(+), Ca super(2+), Mg super(2+), Pi, ammonia, lactic acid and catecholamines were observed as hypoxia progressed. Decreases in heart rate (HR) and blood pressure in dorsal aorta (BPd), and increase in the duration of electrical systole in electrocardiogram were also observed. Increased GFR and urine flow, and higher values for urinary components, except protein, compared with those of the control were found in the initial post-stress stage. Increases in plasma angiotensin II, HR and BPd were also observed. They resumed to the resting levels after 12 hr.