Fig. 2.

Substance P (SP) fails to elicit contraction of isolated rat mesenteric collecting lymphatic vessels when extracellular Ca²⁺ is absent. A: representative trace of diameter over time of an isolated rat collecting lymphatic vessel before and after the addition of SP bathed in normal albumin physiological salt solution (APSS; left) and in Ca²⁺-free APSS (right). The boxes beneath the trace represent the time periods during which diameter was averaged before and after addition of SP, compared in B. Average diameter during a 1-min period between 90 and 30 s before the addition of SP (Before SP), was compared with the 0–30-s and 31–180-s periods after SP was added to the bath by a repeated measures ANOVA followed by Dunnett’s test, which revealed no significant differences. N = 3 lymphatic vessels studied, each obtained from a unique rat. NS, not significant.