6. Afferent Vagal Traffic in Conscious Sheep

The renal sympathetic responses to infusion of hypertonic solutions into the lateral cerebral ventricles were investigated in conscious sheep. Intracerebroventricular infusion of artificial cerebrospinal fluid (CSF) containing 0.6 M NaCl, at 1 ml/h for 20 min, reduced renal sympathetic nerve activity (RSNA) by 81 +/- 5% (n = 6, P < 0.001). Plasma renin concentration also fell (P < 0.05), whereas arterial pressure increased by 6.4 +/- 0.7 mmHg (P < 0.01). Intracerebroventricular hypertonic sorbitol (0.9 M in CSF at 1 ml/h) had no effect. The AT1 receptor antagonist losartan (1 mg/h) abolished the plasma renin and arterial pressure responses to intracerebroventricular hypertonic saline and significantly reduced the fall in RSNA to 17 +/- 10% (P < 0.001). During intracerebroventricular hypertonic saline, the baroreflex relation of RSNA to diastolic pressure was shifted to the left and that to central venous pressure was abolished compared with control relations obtained by manipulating pressure with intravenous phenylephrine. These findings indicate that 1) RSNA is inhibited by a central mechanism that senses high sodium (or perhaps chloride) concentration rather than hypertonicity; 2) this inhibition occurs independently of reflexes from high- and low-pressure baroreceptors, although these may enhance the inhibition; and 3) inhibition of RSNA by hypertonic saline involves a central angiotensinergic pathway.

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Inhibition of ovine gastric acid secretion by intraduodenal long-chain fatty acids

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.1982.243.2.g127 ◽

1982 ◽

Vol 243 (2) ◽

pp. G127-G133

Author(s):

L. M. McLeay ◽

J. M. Fitzgerald

Keyword(s):

Fatty Acids ◽

Fatty Acid ◽

Acid Secretion ◽

Gastric Acid Secretion ◽

Gastric Acid ◽

Unsaturated Fatty Acids ◽

Acid Output ◽

Saturated Fatty Acids ◽

Fatty Acid Content ◽

Conscious Sheep

Effects on ovine gastric function of procedures that increase intestinal unsaturated fatty acid content are unknown, and the present aim was to compare the effects of duodenal unsaturated and saturated fatty acids on gastric secretion in conscious sheep. During the maximal gastric secretory response to a meal, 10 ml gallbladder bile alone or with myristic, palmitic, and stearic acids and oleic, linoleic, and linolenic acids were infused into the duodenum at a rate of 5 g fatty acid . h-1 for 1 h. Compared with control 154 mM NaCl (100%), acid output was reduced to 4-7% of control with infusion of oleic, linoleic, and linolenic acids and myristic acids plus bile. Reductions in acid secretion persisted for up to 5 h from the end of infusion. In contrast, the infusion of palmitic and stearic acids with bile caused mean maximal reductions in acid output, respectively, to only 64 and 55% of control, and levels returned to control within 1 h of the end of infusion. Bile infusion alone caused no reduction in acid secretion. Under the conditions used, C18 unsaturated fatty acids and myristic acid were potent inhibitors of ovine gastric acid secretion. The lesser effects of palmitic and stearic acids were probably related to their reduced solubility and absorption.

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33 Effect of afferent vagal stimulation through oral exposure to a sour or a salty taste on gastric myoelectrical activity evaluated by means of multi-channel electrogastrography

Neurogastroenterology & Motility ◽

10.1111/j.1365-2982.2006.00789_33.x ◽

2006 ◽

Vol 18 (6) ◽

pp. 490-490

Author(s):

M DZIELICKI ◽

K JONDERKO ◽

E DOMOSLAWSKA ◽

M WALUGA ◽

A KASICKA-JONDERKO ◽

...

Keyword(s):

Vagal Stimulation ◽

Oral Exposure ◽

Gastric Myoelectrical Activity ◽

Myoelectrical Activity ◽

Salty Taste ◽

Afferent Vagal

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Effects of medullary afferent vagal axotomy and area postrema lesions on short-term and long-term NaCl-induced taste aversion learning

Physiology & Behavior ◽

10.1016/0031-9384(90)90354-7 ◽

1990 ◽

Vol 47 (6) ◽

pp. 1067-1074 ◽

Cited By ~ 23

Author(s):

M. Arnedo ◽

M. Gallo ◽

A. Agüero ◽

A. Puerto

Keyword(s):

Taste Aversion ◽

Area Postrema ◽

Aversion Learning ◽

Short Term ◽

Taste Aversion Learning ◽

Afferent Vagal

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Thermal responses to central angiotensin II, SQ 20881, and dopamine infusions in sheep

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1985.248.3.r371 ◽

1985 ◽

Vol 248 (3) ◽

pp. R371-R377 ◽

Cited By ~ 2

Author(s):

B. S. Huang ◽

M. J. Kluger ◽

R. L. Malvin

Keyword(s):

Angiotensin Ii ◽

Body Temperature ◽

Enzyme Inhibitor ◽

Renin Angiotensin System ◽

Significant Rise ◽

Ang Ii ◽

Deep Body Temperature ◽

Angiotensin System ◽

Conscious Sheep

The thermoregulatory role of brain angiotensin II (ANG II) was tested by intracerebroventricular (IVT) infusion of ANG II or the converting enzyme inhibitor SQ 20881 (SQ) in 15 conscious sheep. Deep body temperature decreased 0.30 +/- 0.07 degree C (SE) during the 3-h period of IVT ANG II (25 ng/min) infusion (P less than 0.05) and increased 0.50 +/- 0.13 degree C during IVT SQ (1 microgram/min) infusion (P less than 0.01). To determine whether the rise in body temperature after IVT SQ infusion might be the result of a central renin-angiotensin system (RAS), SQ was infused IVT in five conscious sheep 20 h after bilateral nephrectomy. This resulted in a significant rise in body temperature of 0.28 +/- 0.05 degree C (P less than 0.05). When vasopressin antidiuretic hormone (ADH) was infused intravenously at the same time of IVT SQ infusion, the rise in temperature was depressed, but ADH did not lower the temperature below basal. IVT dopamine (20 micrograms/min) increased body temperature by 0.40 +/- 0.04 degree C (P less than 0.01), which was qualitatively similar to the result with IVT SQ. These data support the hypothesis that endogenous brain ANG II may play a role in thermoregulation. Furthermore, plasma ADH level, regulated in part by brain ANG II, is probably not the mediator of that thermoregulation. The similar effects of IVT dopamine and SQ on body temperature strengthen the hypothesis that dopamine may be involved in the central action of brain ANG II.

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Estimation of pituitary secretion rate during the reproductive cycle of sheep

The Journal of Agricultural Science ◽

10.1017/s0021859600072221 ◽

1990 ◽

Vol 114 (2) ◽

pp. 213-218

Author(s):

K. S. Lindsay ◽

I. R. Fleet ◽

D. E. Walters ◽

R. B. Heap

Keyword(s):

Blood Flow ◽

Reproductive Cycle ◽

Hormone Secretion ◽

Pituitary Hormone ◽

Thyrotrophin Releasing Hormone ◽

Releasing Hormone ◽

Pituitary Secretion ◽

Conscious Sheep ◽

Cephalic Blood Flow ◽

Secretion Rates

SUMMARYA technique has been developed for the measurement of pituitary hormone secretion rates in conscious sheep. The technique involves the continuous and simultaneous sampling of blood from the carotid artery and jugular vein and the measurement of cephalic blood flow by an indicator dilution technique. Veno-arterial differences in hormone concentrations multiplied by cephalic blood flow gave average secretion rates which were measured after single or repeated large doses of luteinizing hormone releasing hormone (LHRH) and thyrotrophin-releasing hormone (TRH) at various times in the reproductive cycle.

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