Endocrine and metabolic effects of hypotension or halothane inhalation in sheep anaesthetized with pentobarbital. 1998

P M Taylor
Department of Clinical Veterinary Medicine, University of Cambridge.

We have studied the mechanism whereby halothane induces adrenocortical activity in eight sheep anaesthetized twice for 2 h with pentobarbital. During the second hour they received infusion of nitroprusside to lower mean arterial pressure by 40 mm Hg (group NP) or on another occasion they inhaled 0.5% halothane (group HAL). Plasma concentrations of cortisol, adrenocorticotrophic hormone (ACTH), arginine vasopressin (AVP), glucose and lactate were measured. Infusion of nitroprusside increased cortisol concentrations from mean 44 (SD 33) to 256 (131) nmol litre-1 (P < 0.05), AVP from 19 (14) to 174 (102) pmol litre-1 (P < 0.05) and ACTH from 30 (17) to 54 (32) pmol litre-1. Glucose and lactate concentrations did not change significantly. After 60 min of halothane administration, there were fewer effects: plasma cortisol increased from 47 (39) to 63 (44) nmol litre-1 (P > 0.05) and AVP from 14 (11) to 32 (29) pmol litre-1 (P > 0.05) while ACTH decreased from 32 (13) to 25 (10) pmol litre-1. The AUC60-120 values for all three hormones were significantly lower in group HAL than in group NP (P < 0.01). Glucose was unchanged but lactate concentration decreased. These results support, but do not prove, the hypothesis that hypotension is the main stimulus to pituitary-adrenocortical activity during halothane anaesthesia in sheep. A direct effect of nitroprusside cannot be ruled out.

UI MeSH Term Description Entries
D006993 Hypnotics and Sedatives Drugs used to induce drowsiness or sleep or to reduce psychological excitement or anxiety. Hypnotic,Sedative,Sedative and Hypnotic,Sedatives,Hypnotic Effect,Hypnotic Effects,Hypnotics,Sedative Effect,Sedative Effects,Sedatives and Hypnotics,Effect, Hypnotic,Effect, Sedative,Effects, Hypnotic,Effects, Sedative,Hypnotic and Sedative
D007022 Hypotension Abnormally low BLOOD PRESSURE that can result in inadequate blood flow to the brain and other vital organs. Common symptom is DIZZINESS but greater negative impacts on the body occur when there is prolonged depravation of oxygen and nutrients. Blood Pressure, Low,Hypotension, Vascular,Low Blood Pressure,Vascular Hypotension
D009599 Nitroprusside A powerful vasodilator used in emergencies to lower blood pressure or to improve cardiac function. It is also an indicator for free sulfhydryl groups in proteins. Nitroferricyanide,Sodium Nitroprusside,Cyanonitrosylferrate,Ketostix,Naniprus,Nipride,Nipruton,Nitriate,Nitropress,Nitroprussiat Fides,Nitroprusside, Disodium Salt,Nitroprusside, Disodium Salt, Dihydrate,Disodium Salt Nitroprusside,Nitroprusside, Sodium
D010424 Pentobarbital A short-acting barbiturate that is effective as a sedative and hypnotic (but not as an anti-anxiety) agent and is usually given orally. It is prescribed more frequently for sleep induction than for sedation but, like similar agents, may lose its effectiveness by the second week of continued administration. (From AMA Drug Evaluations Annual, 1994, p236) Mebubarbital,Mebumal,Diabutal,Etaminal,Ethaminal,Nembutal,Pentobarbital Sodium,Pentobarbital, Monosodium Salt,Pentobarbitone,Sagatal,Monosodium Salt Pentobarbital
D010913 Pituitary-Adrenal System The interactions between the anterior pituitary and adrenal glands, in which corticotropin (ACTH) stimulates the adrenal cortex and adrenal cortical hormones suppress the production of corticotropin by the anterior pituitary. Pituitary Adrenal System,Pituitary-Adrenal Systems,System, Pituitary-Adrenal,Systems, Pituitary-Adrenal
D005260 Female Females
D006221 Halothane A nonflammable, halogenated, hydrocarbon anesthetic that provides relatively rapid induction with little or no excitement. Analgesia may not be adequate. NITROUS OXIDE is often given concomitantly. Because halothane may not produce sufficient muscle relaxation, supplemental neuromuscular blocking agents may be required. (From AMA Drug Evaluations Annual, 1994, p178) 1,1,1-Trifluoro-2-Chloro-2-Bromoethane,Fluothane,Ftorotan,Narcotan
D006854 Hydrocortisone The main glucocorticoid secreted by the ADRENAL CORTEX. Its synthetic counterpart is used, either as an injection or topically, in the treatment of inflammation, allergy, collagen diseases, asthma, adrenocortical deficiency, shock, and some neoplastic conditions. Cortef,Cortisol,Pregn-4-ene-3,20-dione, 11,17,21-trihydroxy-, (11beta)-,11-Epicortisol,Cortifair,Cortril,Epicortisol,Hydrocortisone, (11 alpha)-Isomer,Hydrocortisone, (9 beta,10 alpha,11 alpha)-Isomer,11 Epicortisol
D000324 Adrenocorticotropic Hormone An anterior pituitary hormone that stimulates the ADRENAL CORTEX and its production of CORTICOSTEROIDS. ACTH is a 39-amino acid polypeptide of which the N-terminal 24-amino acid segment is identical in all species and contains the adrenocorticotrophic activity. Upon further tissue-specific processing, ACTH can yield ALPHA-MSH and corticotrophin-like intermediate lobe peptide (CLIP). ACTH,Adrenocorticotropin,Corticotropin,1-39 ACTH,ACTH (1-39),Adrenocorticotrophic Hormone,Corticotrophin,Corticotrophin (1-39),Corticotropin (1-39),Hormone, Adrenocorticotrophic,Hormone, Adrenocorticotropic
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia

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