Figure 1. NOS inhibition with LNNA enhances tone in response to intramural pressure changes but not in the presence of a constant pressure.

Vascular diameter was monitored in pressurized segments of male SMAs that were superfused with PSS solution with and without 10 µM LNNA and with Ca²⁺ free solution (0Ca), as indicated by bars located above the traces. During the period of superfusion with LNNA, vessel segments were subjected either to a constant intramural pressure of 60 cmH₂O (black trace) or different intramural pressures as indicated (red trace). Intramural pressures are indicated by bars located below the traces. Note that the vascular diameter at 60 cmH₂O decreased in vessel segments that were exposed to pressure variations but not in vessel segments that were exposed to a constant pressure and that the diameter in Ca²⁺ free solution was similar in both groups. Traces represent averages of 5 vessel segments. Data were acquired at 1 s intervals, however, error bars (sem) were plotted only every 50 s.