Table 1.

Comparison of Ca2+ sparks from vascular SM cells, Ca2+ puffs from Xenopus oocytes, and Ca2+ pulsars from mesenteric endothelium

ParametersCa2+ sparks (26)Ca2+ puffsCa2+ pulsars
Fluo-4GCaMP2
Amplitude, F/Fo2.050–500 nM (27)1.77 ± 0.101.70 ± 0.02
Area, μm213.62–4 (16, 27)15.9 ± 0.614.1 ± 0.5
Rise time, ms22.7<100 (28)212 ± 11163 ± 6
Duration, msn/a1,000 (16, 27)257 ± 12269 ± 6
t1/2, ms55.9375 (15)146 ± 9168 ± 5
Frequency, Hzn/an/a0.10 ± 0.020.08 ± 0.02
  • Descriptive parameters of Ca2+ signals in terms of peak amplitude, area measured at 50% of the amplitude of the peak, rise time as measured during 10–90% of the signal, duration as measured from 50% of the signal before and after the peak, and the half-time for decay (t1/2) of the signal. Ca2+ pulsars differ from Ca2+ puffs in that their area and rise time are significantly greater, yet their duration and half-life are significantly less. Fluo-4 values are from 743 pulsars originating from 56 sites recorded in 4 fields, and GCaMP2 values are from 450 pulsars originating from 45 sites recorded in 4 fields. n/a, not applicable.