The involvement of the sympathetic nervous system in the centrogenic pressor and tachycardiac effects of prostaglandins E2 and F2α in anaesthetised cats

The intracerebroventricular (i.c.v.) administration of prostaglandin E₂ (PGE₂, 1 μg) and prostaglandin F_2α (PGF_2α, 10 μg) produced prolonged pressor and tachycardiac responses in chloralose-anaesthetised cats. Phenoxybenzamine-pretreatment completely prevented the pressor response without altering the tachycardiac response, whereas propranolol intervention completely inhibited the tachycardiac response and also attenuated the pressor response. The pretreatment with pentolinium completely antagonised both the pressor and tachycardiac responses to i.c.v. PGE₂ and PGF_2α. The results suggest that the centrally administered PGE₂ and PGF_2α augment sympathetic outflow to the heart and vascular system and thereby cause excitatory cardiovascular responses in anaesthetised cats.