FIG 6.

Caspofungin effects depend upon Ca²⁺ derived from caffeine-sensitive stores. (A) In Ca²⁺-free buffer medium, caspofungin induced a significant rise in the PTV that slowly decelerated during the exposure period. (B) The basal PTV was not affected by Ca²⁺-free buffer solutions (Wilcoxon rank-sum test). The significant rise in the PTV evoked by caspofungin in Ca²⁺-free buffer solution was significantly lower than that in Ca²⁺-containing buffer solution (Mann-Whitney U test). (C) Mouse tracheae exposed to caffeine (30 mM) in Ca²⁺-free buffer solution did not demonstrate alterations in the PTV. The application of caspofungin to tracheae primarily exposed to caffeine in Ca²⁺-free solution also did not evoke an increase in the PTV. Instead, the PTV slowly decelerated below the basal PTV value. (D) Caffeine (30 mM) in Ca²⁺-free medium did not change the PTV relative to the control in Ca²⁺-free solution (Mann-Whitney U test). The application of caspofungin in the presence of caffeine (30 mM) did not affect the basal PTV. In Ca²⁺-free buffer medium, the PTV level during caspofungin exposure in the presence of caffeine was significantly lower than that measured during sole caspofungin exposure. (■, Ca²⁺-free control buffer medium; ♦, Ca²⁺-free buffer medium with caspofungin; X, Ca²⁺-free buffer medium with caffeine; ▴, Ca²⁺-free buffer medium with caffeine and caspofungin; horizontal bars in experimental recordings present exposure periods of defined pharmacological agents; n, number of individual experiments; ns, not significant; time scale bars are present in all individual panels; **, P < 0.01; ***, P < 0.001; Mann-Whitney U test).