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Investigation of the effects of IVth ventricular administration of the 5‐HT 2 agonist, 1‐(2,5‐dimethoxy‐4‐iodophenyl)‐2‐aminopropane (DOI), on autonomic outflow in the anaesthetized cat
Author(s) -
Shepheard Sara L.,
Jordan David,
Ramage Andrew G.
Publication year - 1991
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1991.tb12437.x
Subject(s) - phrenic nerve , chloralose , blood pressure , heart rate , medicine , splanchnic nerves , anesthesia , vagus nerve , splanchnic , hemodynamics , stimulation , respiratory system
1 The effects of IVth ventricular injections of 1‐(2,5‐dimethoxy‐4‐iodophenyl)‐2‐aminopropane (DOI) on renal, splanchnic and cardiac sympathetic nerve activities, phrenic nerve activity, arterial blood pressure, heart rate, femoral arterial conductance, tracheal and intragastric pressures were investigated in α‐chloralose anaesthetized, neuromuscular blocked and artificially ventilated cats. 2 Cumulative doses of DOI (80, 160 and 320 nmol kg −1 ) injected into the IVth ventricle caused an increase in mean arterial blood pressure, a fall in femoral arterial conductance, an increase in tracheal pressure and a decrease in the rate of phrenic nerve bursts but did not affect any of the other variables recorded. 3 Even after i.v. administration of the peripheral 5‐HT 2 antagonist BW501C67 (2 mg kg −1 ) following the highest dose of DOI there was still a significant pressor response, a fall in femoral arterial conductance and small increase in tracheal pressure. 4 In control experiments, intravenous infusion of noradrenaline to raise blood pressure to the levels obtained during the cumulative doses of DOI caused large falls in renal, splanchnic and cardiac nerve activities which were all significantly lower than those recorded during the cumulative doses of DOI. 5 The results of this study provide evidence for a brainstem site of action of DOI in producing hypertension and further support the hypothesis that central 5‐HT 2 receptors are involved in the control of skeletal muscle and skin vascular beds.