Fig. 6

Ca²⁺ sensitivity of the SMA decreases with increase in pressure. a, b Vascular diameter and [Ca²⁺]_i changes in the presence of 0, 1, 3 and 10 mM Ca²⁺ were simultaneously measured from vessel segments pressurized at 60 cmH₂O (black trace) followed by 40 cmH₂O (red trace), as indicated. a Summary of changes in [Ca²⁺]_i measured as changes in fluorescence intensity. b Summary of corresponding diameter measurements first at 60 cmH₂O and then at 40 cmH₂O (4 arteries). Data were acquired at 1 s intervals, however, for clarity, error bars (sem) are plotted only every 10s. c Ca²⁺ sensitivity of SMA at 60 cmH₂O (black trace) and 40 cmH₂O (red trace). d Ca²⁺ sensitivity of SMA at 60 cmH₂O (black trace) and time control at 60 cmH₂O (grey trace). Numbers next to symbols represent the number of arteries. For c and d, average FC₅₀ values are given as mean ± sem. Data points for normalized [Ca²⁺]_i and diameter were obtained by averaging diameter and fluorescence intensity measurements over the last 30 s of each Ca²⁺ step and normalizing these values against the average value obtained in PSS containing 1 mM Ca²⁺ at 60 cmH₂O (denoted as ‘a’)