Sympathetic nervous control of the vasculature in the tail of the Atlantic cod,Gadus morhua

Summary The effects of some drugs and electrical stimulation of the sympathetic chain on the vasculature of the isolated perfused tail of the cod has been studied. Adrenaline, phenylephrine and isoprenaline all constricted the tail vasculature, isoprenaline also producing dilation in some preparations at lower concentrations (10^–9–10^–6M). Electrical stimulation of the sympathetic chain produces vasoconstriction, which can be abolished by phentolamine in concentrations expected to be selective for -adrenoceptor blockade in the cod. A small dilatory response to nerve stimulation was seen in some preparations after phentolamine. Carbachol produced weak and irregular effects, and a contribution by cholinergic fibres therefore seems unlikely. It is concluded that the excitatory nervous control of the cod tail vasculature is solely by adrenergic sympathetic fibres, which act via an -adrenoceptor mechanism.