Effects of heat stress on Na⁺,K⁺‐ATPase, Mg²⁺‐activated ATPase, and Na⁺‐ATPase activities of broiler chickens vital organs

Abstract

Na+,K(+)-ATPase, Mg(2+)-activated ATPase, and Na(+)-ATPase activities of brain, heart, kidney, and small and large intestinal mucosa of broiler chickens exposed to heat stress (41 degrees C, 65% relative humidity for 6 h) and thermoneutral (25 degrees C, 65% relative humidity) conditions were determined. Brain and kidneys were found to have significantly higher Na+,K(+)-ATPase activities than those of heart and intestinal mucosa. Mg(2+)-activated ATPase and Na(+)-ATPase activities in the intestinal mucosa were higher than those of brain, kidneys, and heart under thermoneutral conditions. While there was a significant inhibition of total ATPase, Na+,K(+)-ATPase, Mg(2+)-activated ATPase, and Na(+)-ATPase activity of small and large intestinal mucosa of broiler chickens exposed to heat stress, the inhibitory effect was limited to total ATPase and Na+,K(+)-ATPase enzymes in kidneys. Heat stress produced a significant increase only in Mg(2+)-activated ATPase activity of the heart, without a remarkable change in all forms of ATPase activity in the brain. Heat stress significantly decreased the ratio of Na+,K(+)-ATPase to Mg(2+)-ATPase in the heart, kidneys, and small and large intestinal mucosa. The percentage of Na(+)-ATPase in Na+,K(+)-ATPase of brain, heart, and kidneys did not significantly change during heat stress, but the ratio in small and large intestinal mucosa increased significantly during heat stress. The severe disturbances in both serum electrolytes and acid-base balance observed in previous heat stress studies could partly be mediated by direct or indirect effects of heat stress on Na+,K(+)-ATPase, Mg(2+)-activated ATPase, and Na(+)-ATPase activities of kidneys, and small and large intestinal mucosa of broiler chickens.

Effects of ambient temperature on broiler mineral balance partitioned into urinary and faecal loss

“…Previous studies have documented that HS exposure reduces blood flow to the intestine (Wolfeson, 1986), digestive tract motility (Tur and Rial, 1985) and digestive enzyme secretion (Osman, 1985). These derangements, coupled with the negative effect of HS on renal and intestinal mucosa Na-K-ATPase activity (Chen et al, 1994), might alter mineral absorption and metabolism. Indeed, findings such as the higher dietary need for potassium of broilers (Smith and Teeter, 1987 a) and laying hens (Deetz and Ringrose, 1976) subjected to HS, and the better performance and survival of heat-stressed birds given drinking water with potassium chloride (Teeter and Smith, 1986), sodium bicarbonate (Gorman and Balnave, 1994) or a complex mineral mix (Belay and Teeter, 1993 b), may be related to the perturbed mineral balances reported here.…”

Transport stress induces weight loss and heart injury in chicks: disruption of ionic homeostasis via modulating ion transporting ATPases

“…The previous investigations demonstrated that high temperature inhibited the mitochondrial Ca 2+ -ATPase activity in broilers [38]. And the heat stress could suppress Na + -K + -ATPase activity and Mg 2+ -ATPase activity of broiler chickens vital organs [39]. The ATPases activities in aquatics, mammals and quails decreased significantly after atrazine exposure [35, 36, 40].…”

“…As an important part of the plasma membrane, Na + -K + -ATPase transports 2K + ions into and 3Na + ions out of the cells using 1ATP hydrolysis. Previous investigations have demonstrated that the heat stress significantly reduced Na + -K + -ATPase in the intestinal mucosa of chickens [39, 42]. The atrazine exposure could induce Na + , K + disorders via disruption of Na + -K + -ATPase [35, 36, 40].…”

Pathophysiology of avian intestinal ion transport

“…Heat exposure reduced the gene expression of glucose transporter 2 (GLUT-2) which diffuses monosaccharides from the basolateral side of intestinal epithelial cells into the extracellular fluid, fatty acid binding protein FABP1, and fatty acid receptor CD36 in broiler chicken (Sun et al , 2015). The serum electrolyte and acid-base imbalances seen in broiler chicken exposed to heat are thought to be mediated by reduced activity of Na + K + ATPase, Mg 2 + -activated ATPase, and Na + -ATPase in the intestine and kidney (Chen et al , 1994). While ion transport and digestive activity is optimised to a certain degree in the face of reduced feed intake and decreased absorptive compartment (decreased intestinal surface area) caused by the heat exposure (Mitchell and Carlisle, 1992), the threshold of physiological responses under such conditions requires further investigation.…”