Abstract

Introduction

Materials & Methods

Results

Discussion & Conclusion

References

Discussion
Board

Male Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR) fed low salt (0.45%, LS) or high salt (7%, HS) diets for 4-5 weeks were anesthetized with sodium thiopental (100 mg/kg, i.p.). Each rat was enclosed in a ventilated box. The right spinotrapezius muscle was surgically exteriorized through a slit in the box for observation with intravital microscopy. Large arcade bridge arterioles connecting proximal and distal feed arteries were studied. In the first group of experiments, microvascular transmural pressure was increased in the exteriorized muscle by raising the ambient box pressure to 10, 20 and 30 mm Hg above atmospheric pressure, with a recovery period after each pressurization step. These pressure steps were then repeated under NO synthase inhibition with NG-monomethyl-L-arginine (10^-4 M, L-NMMA). L-NMMA specificity was evaluated in a second group of experiments by pressurizing the box under the normal superfusate, during L-NMMA superfusion and then during simultaneous exposure to L-NMMA and excess L-arginine (5x10^-3 M). Microvascular pressures were measured (via servo-null) in a third group of experiments to verify that increases in arterial pressure were transmitted completely and equally to the arterioles of each group. Passive arteriolar diameters were determined during superfusion with 5x10^-4 M adenosine. To evaluate any secondary effects of arteriolar shear stress on diameter (D), an escape index was calculated:[D_FINAL-D_MINIMUM]/[D_CONTROL-D_MIMIMUM].

Back to the top.