Alpha Adrenergic Regulation of Celiac Blood Flow and Plasma Catecholamine Response During Acute Heat Stress in Fed Cockerels

Abstract

Hubbard cockerels with chronically implanted electromagnetic blood flow probes on the celiac artery were used to establish a relationship between changes in postprandial celiac mean blood flow (MBF) and plasma catecholamines during a acute heat exposure. Five min after the elevation of ambient temperature from 25 to 37 C, there were concomitant reductions (P less than .05) in celiac MBF, norepinephrine (NE), and heart rate (HR). After 50 min of heat stress, rectal temperature (Tr), respiratory rate (RR), plasma epinephrine (E), and celiac vascular resistance (CVR) were significantly greater (P less than .05) than preheat stress thermoneutral control values. During the thermoneutral recovery period, all parameters returned to values comparable to preheat exposure control with the exception of NE, which tended (P less than .1) to remain lower. To determine the role of the sympathetic nervous system in regulating postprandial celiac MBF during acute heat exposure, chronically instrumented cockerels were infused with phenoxybenzamine, an alpha-adrenergic receptor-blocking agent. Alpha-receptor blockade attenuated both postprandial intestinal hyperemia under thermoneutral conditions as well as the heat-induced reduction of postprandial celiac MBF. The results of these studies implicate the sympathetic nervous system in the regulation of postprandial celiac MBF in heat-stressed cockerels and indicate a possible alpha-adrenergic-mediated mechanism involved in postprandial intestinal hyperemia.

Changes in free amino acid concentrations in the blood, brain and muscle of heat-exposed chicks

“…However, we could not preclude the possibility that the heat stress response was due to the activation of the sympathetic nervous system. Bottje and Harrison (1986) reported that after 50 min of heat treatment rectal temperature, respiratory rate and plasma epinephrine were significantly greater in cockerels than in control birds. Thus, further research is needed to measure plasma epinephrine and norepinephrine when chicks are exposed to a short period of HT.…”

The Effect of High Ambient Temperature and Hypercapnia on Postprandial Intestinal Hyperemia in Domestic Cockerels

“…Thus, in the present study, heat-induced sympathetic vasoconstriction may have superceeded any potential vasomotion that might be produced by changes in blood PC0 2 . Studies designed to determine the relative importance of the sympathetic nervous system in the regulation of intestinal blood flow in heatexposed fowl are presented in a companion paper (Bottje and Harrison, 1986).…”

Resveratrol alleviates heat-stress-induced impairment of the jejunal mucosa through TLR4/MAPK signaling pathway in black-boned chicken

“…When the heat dissipation mechanism is activated in their body, it redistributes blood flow for self-protection. In this case, generally, blood tends to flow from internal organs to other parts with evaporative heat dissipation functions, such as limbs and skin, increasing blood flow to these body parts ( Wolfenson et al, 1981 ; Bottje et al,1986 ). This leads to decreased blood flow toward digestive organs such as the gastrointestinal tract, causing intestinal hypoxia and ischemia, apoptosis of epithelial cells, shortening of intestinal villi, increased intestinal permeability, damage to the intestinal mucosal barrier, and obstruction of nutrient absorption and transport ( Sun et al, 2015 ; Liu et al,2016 ).…”