Effects of α- and β-adrenergic receptor stimulation and oxytocin receptor blockade on milking characteristics in dairy cows before and after removal of the teat sphincter

2003 ◽  
Vol 70 (3) ◽  
pp. 289-292 ◽  
Author(s):  
Tyra Inderwies ◽  
Johannes Riedl ◽  
Evangelos Kiossis ◽  
Rupert M. Bruckmaier
Keyword(s):  
Milk Yield ◽  
Adrenergic Receptor ◽  
Peak Flow ◽  
Muscle Tone ◽  
Blocking Agent ◽  
Receptor Blockade ◽  
Adrenergic Stimulation ◽  
Receptor Stimulation ◽  
Milk Flow ◽  
Before And After

Alpha (α)- and beta (β)-adrenergic receptors in the bovine mammary gland are mainly present in the teat muscles and in the region where large milk ducts reach the cisternal cavities. The aim of the study was to test the hypothesis that the region of the large mammary ducts is the most important location of α- and β-adrenergic receptor stimulation affecting milk ejection and milk removal. Effects of α- and β-adrenergic receptor stimulation and of oxytocin (OT) receptor blockade on milking characteristics were tested in six cows. Milk flow was measured before and after the distal part of one teat, including the teat canal and teat sphincter, had been partly amputated. Before the operation, milk yield and peak flow rate decreased during α-adrenergic receptor stimulation and during the OT receptor blockade, and increased during β-adrenergic stimulation. After removal of the teat tip, relations of milk yield and peak flow rates after administration of α- and β-agonists and after application of an OT receptor blocking agent were similar to those before operation. Only total milk yield had decreased in the teat-amputated quarter owing to unhindered flow of cisternal milk before cluster attachment. Since responses to α- and β-adrenergic receptor stimulation as well as to OT receptor blockade do not differ with or without the teat sphincter, it is concluded that milk flow is mainly influenced by the muscle tone of the large mammary ducts.

Inhibition of milk ejection in cows by oxytocin receptor blockade, α-adrenergic receptor stimulation and in unfamiliar surroundings

1997 ◽  
Vol 64 (3) ◽  
pp. 315-325 ◽  
Author(s):  
RUPERT M. BRUCKMAIER ◽  
OLGA WELLNITZ ◽  
JÜRG W. BLUM
Keyword(s):  
Adrenergic Receptor ◽  
Peak Flow ◽  
Oxytocin Receptor ◽  
Receptor Blockade ◽  
Milk Ejection ◽  
Receptor Stimulation ◽  
Flow Rates ◽  
Milk Flow ◽  
Drug Treatments ◽  
Similar Peak

Inhibition of milk ejection in cows by oxytocin receptor blockade (Atosiban) and α-adrenergic receptor stimulation (phenylephrine) prior to prestimulation was compared with inhibition of milk ejection in unfamiliar surroundings. In addition, Atosiban and phenylephrine were administered after a 1 min prestimulation or 1 min after the start of milking. Oxytocin concentrations increased during milking in all treatments. The spontaneously removed milk fraction (before oxytocin was injected) was similar for Atosiban and phenylephrine treatments and in unfamiliar surroundings, but lower than in controls. Peak flow rates were similar in all treatments, but reduced as compared with controls when phenylephrine and Atosiban were administered before prestimulation. Peripheral (Atosiban, phenylephrine) and central (unfamiliar surroundings) inhibition of milk ejection reduced the amount of available milk similarly. Drug treatments resulted in similar peak flow rates; however, teats were contracted after phenylephrine administration but not after Atosiban. The inhibition induced by Atosiban could be abolished by oxytocin injection, but not that induced by phenylephrine, which was antagonized by α-adrenergic receptor blockade. These results indicate that inhibition of milk ejection through activation of α-adrenergic receptors is based on blockade of milk flow into the cistern, but not through the teats.

Adrenergic stimulation and blockade in colonic circulation of the rhesus monkey

1981 ◽  
Vol 240 (1) ◽  
pp. G25-G31
Author(s):  
J. C. Kerr ◽  
K. G. Swan
Keyword(s):  
Adrenergic Receptor ◽  
Arterial Blood Flow ◽  
Receptor Blockade ◽  
Adrenergic Stimulation ◽  
Beta Adrenergic Receptor ◽  
Receptor Stimulation ◽  
Beta Adrenergic ◽  
Alpha Adrenergic Receptor ◽  
Arterial Blood ◽  
Adrenergic Receptor Blockade

Adrenergic stimulation and blockade on inferior mesenteric arterial blood flow (Q) were measured in anesthetized rhesus monkeys. Control Q was 25 +/- 2 (mean +/- SE) ml/min; aortic and portal venous pressures were 121 +/- 5 and 6.5 +/- 1.0 mmHg. Calculated inferior mesenteric arterial resistance was 5.10 +/- 0.42 peripheral resistance units. Norepinephrine (N), 10(-3) to 1.0 microgram/kg intra-arterially, caused dose-dependent decreases in Q. Epinephrine (E) increased Q at 10(-3) microgram/kg in 60% of the animals studied and decreased Q at the higher doses (10(-2) to 1.0 microgram/kg). Isoproterenol (I) increased Q at all four doses studied. Ten-minute infusions of N and E (0.5 microgram x kg-1 x min-1) caused sustained decreases, and I caused sustained increases in Q. Autoregulatory escape was not observed. alpha-Adrenergic receptor blockade (phenoxybenzamine) attenuated the vasoconstrictor responses to N, but did not "reverse" the vasoconstrictor response to E (vasodilation). beta-adrenergic receptor blockade (propranolol) attenuated the vasodilator responses to I, but did not alter significantly the responses to E or N. These data indicate that in the monkey colonic circulation, alpha-adrenergic receptor stimulation causes vasoconstriction and beta-adrenergic receptor stimulation causes vasodilation.

Increased alpha 1-adrenergic vascular sensitivity during development of hypertension in conscious dogs

1993 ◽  
Vol 264 (4) ◽  
pp. H1259-H1268 ◽  
Author(s):  
N. Uemura ◽  
D. E. Vatner ◽  
Y. T. Shen ◽  
J. Wang ◽  
S. F. Vatner
Keyword(s):  
Adrenergic Receptor ◽  
Peripheral Resistance ◽  
Aortic Pressure ◽  
Conscious Dogs ◽  
Aortic Tissue ◽  
Ang Ii ◽  
Receptor Density ◽  
Adrenergic Stimulation ◽  
Before And After ◽  
Vascular Responsiveness

The goal of this study was to determine whether enhanced vascular responsiveness during the development of perinephritic hypertension is selective or nonspecific. The effects of graded infusions of norepinephrine (NE), phenylephrine (PE), angiotensin II (ANG II), and vasopressin (VP) were examined on mean arterial pressure, total peripheral resistance (TPR), and aortic pressure-diameter relationships in conscious dogs. NE increased TPR significantly greater (P < 0.01) in hypertension than normotension, as did PE infusion, whereas ANG II and VP increased TPR similarly before and after hypertension. Analysis of aortic pressure-diameter relationships also demonstrated significant (P < 0.05) shifts in response to NE and PE, but not ANG II and VP, during the development of hypertension. In normotensive dogs, low doses of ANG II infusion also enhanced the vasoconstrictor response not only to NE and PE but also to VP. In contrast to what was observed in hypertension, in the presence of ANG II infusion after ganglionic blockade, enhanced responses to PE and NE were no longer observed. The alpha 1-adrenergic receptor density in membrane preparations from aortic tissue, as determined by [3H]prazosin binding, was higher (P < 0.05) in hypertensive dogs than control dogs. Thus the vascular responsiveness in the aorta and resistance vessels is enhanced to alpha 1-adrenergic stimulation, but not to all vasoconstrictors, during developing perinephritic hypertension. The mechanism appears to involve increased alpha 1-adrenergic receptor density.

Systemic arterial pressor responses induced by potassium in dogfish, Squalus acanthias

1981 ◽  
Vol 241 (3) ◽  
pp. R228-R232
Author(s):  
D. F. Opdyke ◽  
R. G. Carroll ◽  
N. E. Keller
Keyword(s):  
Pressor Response ◽  
Muscle Tension ◽  
Plasma Catecholamines ◽  
Blocking Agent ◽  
Adrenergic Stimulation ◽  
Direct Exposure ◽  
Pressor Responses ◽  
Before And After ◽  
K Concentration

Intravascular injection of small doses of potassium (0.025-0.5 meq) into dogfish results in dose-related dorsal aortic pressor responses. The responses are blocked by phentolamine, an alpha-adrenergic blocking agent. Assays of plasma catecholamines before and after injection of potassium (K+) showed that plasma levels of epinephrine (E) and norepinephrine (NE) had increased significantly (E, 314%; NE, 233%) 1 min after injection. The pressor responses were initiated 40-90 s after K+ injection at which time plasma E and NE levels were already significantly elevated. Experiments on isolated dogfish arterial strips showed that phentolamine cannot block the increase in vascular smooth muscle tension that occurs after direct exposure to small increases (0.003 meq/ml) in K+ concentration. Because phentolamine effectively blocks the pressor response to even higher doses of K+ in vivo, it is thought that, in addition to any direct vasoconstrictor effect or K+, the adrenergic stimulation provided by catecholamine release is required to produce the observed pressor response.

Splenic contraction-induced increases in arterial O2 reduce requirement for CBF in conscious dogs

1995 ◽  
Vol 269 (2) ◽  
pp. H491-H503 ◽  
Author(s):  
N. Sato ◽  
Y. T. Shen ◽  
K. Kiuchi ◽  
R. P. Shannon ◽  
S. F. Vatner
Keyword(s):  
Adrenergic Receptor ◽  
Conscious State ◽  
Conscious Dogs ◽  
Receptor Blockade ◽  
Sympathomimetic Amines ◽  
Blood Flows ◽  
Before And After ◽  
Myocardial O2 Consumption ◽  
Consequent Increase ◽  
Adrenergic Receptor Blockade

We investigated the extent to which sympathomimetic amines induced splenic contraction and associated increases in arterial O2 content (CaO2) and how these mechanisms affected control of the coronary circulation by sympathomimetic amines in conscious dogs. Blood hemoglobin (Hb) and CaO2 increased by 16 +/- 2 and 18 +/- 2%, respectively, during norepinephrine (NE, 0.8 micrograms.kg-1.min-1 iv) in the intact, conscious state after splenic contraction. Phenylephrine (PE) induced similar effects. After either alpha 1-adrenergic-receptor blockade or splenectomy, these effects were abolished. Isoproterenol (Iso) also decreased splenic thickness, which was abolished after ganglionic, alpha-, or beta 1/beta 2-adrenergic-receptor blockade. Direct infusions of NE and PE into the splenic artery decreased splenic thickness and increased Hb and CaO2, whereas Iso had no effect. After splenectomy, NE did not increase CaO2, but coronary blood flow (CBF) increased more (73 +/- 6%) vs. before splenectomy (49 +/- 7%) without any differences before and after splenectomy in the responses of pressures, contractility, and myocardial O2 consumption (MVO2). In contrast, renal, mesenteric, and iliac artery blood flows were not significantly different in response to sympathomimetic amines before and after splenectomy. These data indicate that sympathomimetic amines induced splenic contraction either directly or reflexly via alpha-adrenergic-receptor stimulation. The consequent increase in Hb and CaO2 allows for equivalent increases in MVO2, but at a smaller increase in CBF.

scholarly journals Pre-milking mechanical teat stimulation and milking performance of dairy buffaloes in early lactation

2017 ◽  
Vol 48 (1) ◽  
pp. 53-55
Author(s):  
Francesco Maria Tangorra ◽  
Stefania Leonardi ◽  
Valerio Bronzo ◽  
Nicola Rota ◽  
Paolo Moroni
Keyword(s):  
Milk Yield ◽  
Flow Rate ◽  
Peak Flow ◽  
Early Lactation ◽  
Peak Flow Rate ◽  
Flow Rates ◽  
Enhancing Effect ◽  
Milk Flow ◽  
Total Milk ◽  
Automatic Removal

The objective of the present study was to investigate the effect of pre-milking mechanical teat stimulation on milk yield and milking performance of dairy buffaloes in early lactation. For this purpose, twenty-two healthy Italian Mediterranean buffaloes in their first to third lactation and in early lactation (<120 days in milk) were subjected to two treatments of teat stimulation: i) washing of the teats with water for about 5 s and attaching of the milking unit within 60 s, without any pre-milking massage (farm milking routine); ii) fast pulsation (FP), achieved by increasing pulsation rate to 120 pulsations per min during the first 60 s after application of teat cups. Each treatment lasted for 10 days and the following parameters were measured: milk yield (kg/milking), milk yield at 2 min after unit attachment (kg), time between milking unit attachment and its automatic removal (min), peak milk flow rate (kg/min), and milking time to reach peak flow rate (min). The average milk flow rate (kg/min) was calculated by dividing milk yield by the actual milking time. Milk yield was not affected by mechanical pre-stimulation and during the first 2 min of milking 20.2% and 19.6% of total milk yield were milked respectively when treatments 1 and 2 were applied. The time elapsed from attachment of the milking cluster until its automatic removal was less than 8 min both for buffaloes subjected to FP, and for buffaloes subjected just to washing of the teats before attaching the milking unit. FP stimulation did not show an enhancing effect on peak and average milk flow rates and on milking time to reach peak flow rate.

scholarly journals Quarter milking parameters by lactation in dairy cows

2019 ◽  
Vol 69 (2) ◽  
pp. 108-115
Author(s):  
Ramutė Mišeikienė ◽  
Saulius Tušas ◽  
Paulius Matusevičius ◽  
Sigita Kerzienė
Keyword(s):  
Dairy Cows ◽  
Milk Yield ◽  
Peak Flow ◽  
Dispersion Analysis ◽  
Model Distribution ◽  
Anova Model ◽  
Milk Flow ◽  
Data Collection And Analysis ◽  
Kolmogorov Smirnov ◽  
Smirnov Test

The study was conducted on 229 dairy cows in Lithuania. DeLaval milking robots were used for cows’ milking. Milk yield (kg), milking duration (min), milk flow (kg/min), peak flow rates (kg/min) by cow lactation in separate udder quarters were analyzed. The statistical analysis of the research data was performed using the data collection and analysis program package Statistical Package for Social Science 22 for Windows, Kolmogorov-Smirnov test and One-Factor Dispersion Analysis (ANOVA) model. Distribution of the udder quarters is very important in the cow milking process. Milk yield from cow front udder quarters was about 4.6 kg (42.2 %) and from rear udder quarters 6.32 kg (57.8 %) (P&lt;0.05). The milk content in front quarters was significantly lower than in the rear udder quarters in all dairy cows (P&lt;0.05). Cows of the first lactation showed lower milk production per milking in all udder quarters when compared to other lactation cows (P&lt;0.05). The duration of milking of cows in third and more lactation in front quarters was shorter than that of the first lactation cows (P&lt;0.005). Along the increase in the number of cows’ lactations, the milking time in the front quarters decreased. The average milk flow and the peak flow in the first lactation cows were found to be lower than that in older cows (P&lt;0.05).

Effects of beta-adrenergic receptor blockade on glycogenolysis during exercise

1982 ◽  
Vol 53 (3) ◽  
pp. 549-554 ◽  
Author(s):  
A. C. Juhlin-Dannfelt ◽  
S. E. Terblanche ◽  
R. D. Fell ◽  
J. C. Young ◽  
J. O. Holloszy
Keyword(s):  
Skeletal Muscle ◽  
Adrenergic Receptor ◽  
Beta Blockade ◽  
Receptor Blockade ◽  
Adrenergic Stimulation ◽  
Glycogen Depletion ◽  
Beta Adrenergic Receptor ◽  
Beta Adrenergic ◽  
Adrenergic Receptor Blockade ◽  
Exogenous Substrates

The purpose of this study was to determine whether beta-adrenergic receptor blockade inhibits glycogen utilization in rats during exercise. Propranolol (1 mg/kg body wt) completely blocked the glycogenolytic effect of a large dose of epinephrine given by injection but did not prevent glycogen breakdown in skeletal muscle or liver during a bout of treadmill exercise. On the contrary, exercise resulted in greater glycogen depletion in plantaris muscles of beta-blocked rats than in those of control rats, probably as a result of decreased availability of fatty acids. Increasing the availability of exogenous substrates slowed the rate of skeletal muscle glycogen depletion during exercise. However, even with increased availability of exogenous substrates, beta-blockade did not result in reduced utilization of skeletal muscle or liver glycogen. In contrast to its effect on skeletal muscle, beta-blockade markedly reduced glycogen depletion in the heart during exercise. We conclude that beta-adrenergic stimulation is of major importance in mediating glycogenolysis in the heart but is not necessary for glycogenolysis in skeletal muscle or liver during prolonged exercise.

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