Reflex responses evoked by ventricular mechano and chemo-sensitive afferents (original) (raw)

The left ventricle is richly innervated by non-myelinated nerves1 which can be excited by mechanical or chemical stimuli or both.2 However, because of the difficulty in applying discrete stimuli to these nerves, there have been no studies which have compared the reflex responses to chemical and mechanical stimuli in the same animals. In this study we compared the responses to injection of chemical stimulants into the coronary arteries with those to changes in ventricular pressures. Dogs were anaesthetised with chloralose (100 mg / kg i.v.) and artificially ventilated. A cannula inserted in the aortic root controlled coronary perfusion pressure, whilst a pig-tail balloon catheter was positioned to occlude the aortic valve and isolate the left ventricle from the coronary circulation. End-diastolic pressure was changed by changing ventricular inflow and pressure applied to a Starling resistor controlled ventricular outflow and thus systolic pressure. Veratridine (30-60 µg) was injected...