Effects of Prolonged Intravenous Infusions of Adrenaline on Glucose Utilization, Plasma Metabolites, Hormones and Milk Production in Lactating Sheep

Leenanuruksa, D; McDowell, GH

doi:10.1071/bi9850197

Cited by 12 publications

(4 citation statements)

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“…If this effect is mediated by H 1 receptors, it would explain the negative effect of CPA on milk yield. Milk fat content decreased by 16% when milk ejection was inhibited by continuous epinephrine infusion into goats (Leenanuruksa and McDowell, 1985) but we observed no effect on percentages of protein, fat, or lactose in milk.…”

Section: Role Of Histamine In Milk Secretioncontrasting

confidence: 74%

The Histamine H1 Receptor Is Not Involved in Local Control of Mammary Blood Flow in Dairy Cows

Madsen

Trout

Cieslar

et al. 2008

Journal of Dairy Science

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Low concentrations of the essential amino acid histidine in circulation have been shown to increase mammary blood flow and it has been suggested that this effect is mediated by histamine. The hypotheses tested in this experiment were that interstitial histamine concentrations in the mammary gland are related to arterial His concentrations and that mammary blood flow is reduced by extracellular histamine via H(1) receptors. The hypotheses were tested by infusing saline or chlorpheniramine, a blocker of the H(1) histamine receptor, into the arterial supply of the mammary glands of lactating cows infused with 44 g/h of amino acid mixtures with or without His for 10 h. Infusates were administered in a 2 x 2 factorial arrangement within a 4 x 4 Latin square to 4 multiparous Holstein cows in mid lactation. Exclusion of His from the infusate decreased protein content in milk from the infused udder half from 3.98 to 3.77%, and increased arterial alpha-aminonitrogen concentration from 3.2 to 3.4 mM. Neither the decreased arterial His concentration nor the H(1) blocker affected plasma flow to the infused udder half. We conclude that histamine is not involved in the regulation of mammary blood flow. The H(1) blocker decreased milk production in the infused udder half from 4.6 to 3.5 kg without affecting protein, fat, and lactose percentages, suggesting an inhibition of milk ejection. Cows on chlorpheniramine ate less feed during the infusion than saline-infused cows, which resulted in lower arterial concentrations and mammary uptakes of acetate. The efficiency of plasma triacylglycerol uptake across the mammary glands was decreased by chlorpheniramine but net uptake of long-chain fatty acids was not affected. The mechanism by which an amino acid deficiency influences mammary blood flow does not involve histamine signaling through the H(1) receptor and remains unidentified.

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Section: Role Of Histamine In Milk Secretioncontrasting

confidence: 74%

The Histamine H1 Receptor Is Not Involved in Local Control of Mammary Blood Flow in Dairy Cows

Madsen

Trout

Cieslar

et al. 2008

Journal of Dairy Science

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“…Basal plasma concentrations and secretion rates of insulin, glucagon and growth hormone, and insulin sensitivity were reduced with low energy intake in sheep (Metcalf and Weekes, 1990; Ostaszewski et al., 1990). Epinephrine, one of the stress hormones, is stimulated by cold exposure and induces hyperglycaemia by enhancing glucose production in sheep (Leenanuruksa and McDowell, 1985; Sano et al., 1996). Thyroid hormones have glucoregulatory functions and enhance basal metabolism (Blum et al., 1980).…”

Section: Discussionmentioning

confidence: 99%

Effects of dietary energy intake and cold exposure on kinetics of plasma glucose metabolism in sheep

Sano

Sawada

Takenami

et al. 2006

Animal Physiology Nutrition

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An isotope dilution method using [U-(13)C]glucose injection was applied to determine the effects of dietary energy intake and cold exposure on plasma glucose metabolism in sheep. The sheep were assigned to two dietary treatments and were fed on diets containing either 100% or 160% of ME and both containing 150% of dietary crude protein intake for maintenance. The sheep were exposed from a thermoneutral environment (23 degrees C) to a cold environment (2-4 degrees C) for 5 days. The isotope dilution method was performed on the 18th day in the thermoneutral environment and on the fifth day of cold exposure. Plasma concentrations of glucose and NEFA increased (p < 0.05) during cold exposure for both diets. Plasma glucose pool size remained unchanged (p = 0.67), but plasma glucose turnover rate tended to increase (p = 0.07) with increased energy intake. Both pool size and turnover rate of plasma glucose increased (p = 0.01 and p = 0.0001, respectively) during cold exposure. No significant diet x environment interaction was detected. It is concluded that plasma glucose metabolism was influenced by both dietary energy intake and cold exposure, and plasma glucose metabolism in response to cold exposure was not modified by energy intake in sheep under the conditions (2-4 degrees C on the fifth day) of the present experiment.

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“…It is possible that hormones mediated the 20% decline in milk yield. Adrenaline release from the adrenal glands is stimulated by ammonia (Slawski et al 1984) and exogenous adrenaline reduces milk yield (Gorewit & Aromando, 1985; Leenanuruksa & McDowell, 1985). Exogenous insulin can stimulate milk synthesis (Mackle et al 2000) but plasma insulin concentration is generally increased during hyperammonaemia (Strombeck et al 1981; Slawski et al 1984) so insulin does not make a likely candidate to explain the decreased milk yield.…”

Section: Discussionmentioning

confidence: 99%

The effect of short-term hyperammonaemia on milk synthesis in dairy cows

Purdie

Trout

Cieslar

et al. 2008

Journal of Dairy Research

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To test the hypothesis that ammonia detoxification in ruminants consumes amino acids to the detriment of milk protein production, we infused four lactating dairy cows with ammonium acetate or sodium acetate in switchback experiments. Plasma ammonia concentrations increased to 411 microm within 1 h of the start of infusion of ammonium acetate at 567 mmol/h. The rate constant for ammonia clearance from plasma was 0 x 054/min and the half-life was 12 x 9 min. Infusion at 567 mmol/h for 1 h followed by 1 h without infusion, repeated four times between am- and pm-milking, caused a decrease in feed intake. Compared with sodium acetate, continuous infusion of ammonium acetate at 360 mmol/h throughout an entire 10-h milking interval increased plasma ammonia concentrations to 193 microm and caused a 20% decrease in milk, protein and lactose production with no effect on percentage composition of milk or the yield of milk fat. Arterial concentrations of glucose and non-esterified fatty acids tended to increase; there was no effect on arterial acetate, beta-hydroxybutyrate or triacylglcerol, and branched-chain amino acids, Lys and Thr decreased. Mammary plasma flow, estimated by assuming 100% uptake/output of Phe+Tyr, was significantly correlated with milk yield. Mammary uptakes of acetate tended to be reduced by hyperammonaemia, but uptakes of other energy metabolites and amino acids were not affected. Thus, while an increase in amino acid consumption during hyperammonaemia was apparent from the drop in circulating concentrations of Leu, Ile, Val, Lys and Thr, there was no evidence to support the hypothesis that milk yield is affected by the lower concentrations. An ammonia-induced depression in feed intake may have caused the decrease in milk synthesis.

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Effects of Prolonged Intravenous Infusions of Adrenaline on Glucose Utilization, Plasma Metabolites, Hormones and Milk Production in Lactating Sheep

Cited by 12 publications

References 0 publications

The Histamine H1 Receptor Is Not Involved in Local Control of Mammary Blood Flow in Dairy Cows

The Histamine H1 Receptor Is Not Involved in Local Control of Mammary Blood Flow in Dairy Cows

Effects of dietary energy intake and cold exposure on kinetics of plasma glucose metabolism in sheep

The effect of short-term hyperammonaemia on milk synthesis in dairy cows

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