Figure 2. Responses of ischaemically sensitive cardiac afferents to PRP+collagen before and after the blockade of 5-HT₃ receptors.

A, discharge frequencies of nine cardiac sympathetic afferents before (□) and after (▪) injection of PRP+collagen (1.5 ml, LA). B, effect of PRP+collagen on mean activity of eight separate cardiac afferents before (- tropisetron) and after (+tropisetron) tropisetron (300 μg kg⁻¹, i.v.). C, neurograms displaying responses of an ischaemically sensitive cardiac C-fibre (CV = 0.45 m s⁻¹) to PRP+collagen (1.5 ml, LA) before (Ca) and after (Cb) administration of tropisetron (300 μg kg⁻¹, i.v.). This cardiac afferent innervated the posterior wall of the left ventricle. Data are presented as means ± s.e.m. * P < 0.05 compared with control; † P < 0.05, post-tropisetron vs. pre-tropisetron.