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Acidaemia produced by spinal stimulation in the pithed rat
Author(s) -
Atkinson Judith M.,
Dusting G. J.,
Rand M. J.
Publication year - 1973
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.1973.sp010343
Subject(s) - phenoxybenzamine , guanethidine , stimulation , endocrinology , medicine , chemistry , adrenal medulla , gallamine triethiodide , sympathetic nervous system , adrenergic , adrenalectomy , catecholamine , blood pressure , receptor
1. Electrical stimulation of the thoraco‐lumbar spinal nervous outflow in the pithed rat preparation produces a fall in arterial blood pH. 2. A component of the acidaemic response results from stimulation of skeletal muscle, since the acidaemic response is reduced when contractions of muscle are blocked with gallamine. 3. The residual acidaemic response in gallamine‐treated rats is reduced by adrenalectomy, suggesting that catecholamines liberated from the adrenal medulla may mediate part of the effect. 4. Guanethidine reduces the acidaemic response remaining in adrenalectomized, gallamine‐treated rats, suggesting that the effect of noradrenaline released from sympathetic nerve endings contributes to the fall in pH. 5. Neither phenoxybenzamine nor propanolol alone significantly reduces the acidaemic response in gallamine‐treated rats, but a combination of the two antagonists almost abolishes the effect. Hence the acidaemia is mediated through effects of catecholamines on both α‐ and β‐adreno‐receptors. 6. Since acidaemia affects responses to sympathetic nerve stimulation and sympathomimetic amines, the significance of these observations is discussed with reference to the use of the pithed rat preparation for assessment of drugs affecting adrenergic mechanisms.