1. The use of isolated blood vessels to investigate the physiological and pharmacological control of the vasculature is limited by the requirement to use freshly isolated vessels. Hence, the aim of this study was to determine whether vascular smooth muscle and endothelial cell function could be preserved in resistance arteries by storing them in physiological salt solution (PSS) at 4 degrees C. 2. Third order mesenteric resistance arteries (mean internal diameter 237+/-6 microm) were dissected from the mesenteric bed of male Cob-Wistar rats. The vessel segments were mounted in a small vessel myograph for measurement of isometric tension, and equilibrated at their optimum resting force. Contractile responses to noradrenaline (NA; 1 x 10(-9) - 3 x 10(-5) M), phenylephrine (PE, 1 x 10(-9)-3 x 10(-5) M), potassium chloride (KCI; 2.5-140 mM) and endothelin (ET-1, 1 x 10(-11)-3 x 10(-7) M) and relaxant responses to acetylcholine (ACh; 1 x 10(-9) - 3 x 10(-5) M) and 3-morpholinosydnonimine (SIN-1; 1 x 10(-9) - 1 x 10(-4) M) were obtained in arteries, immediately after dissection (day 0) and following one to four days storage (day 1-day 4). 3. All arteries produced concentration-dependent contractions in response to each of the vasoconstrictors. There were no significant differences in the magnitude or sensitivity (pD2) of the vasoconstrictor responses between fresh and stored vessels. 4. Arteries precontracted with NA to approximately 80% of the maximum response, relaxed in a concentration-dependent manner in response to ACh and SIN-1. Vessel storage for up to three days resulted in no change in response to ACh or SIN-1. 5. Vessels analysed after four days of storage demonstrated a significant increase in sensitivity to ACh and SIN-1 (-logIC50 (M) values; ACh; day 0, 7.46+/-0.13 vs day 4, 7.97+/-0.11, P<0.01 and SIN-1; day 0, 4.87+/-0.10 vs day 4, 5.52+/-0.08, P<0.01). There was also a significant increase in the maximum relaxant response to ACh after four days of storage (% relaxation; day 0, 92.65+/-2.84 vs day 4, 100.36+/-0.36, P<0.05). 6. These results demonstrate that small resistance arteries remain viable if stored in PSS at 4 degrees C for up to four days, with no loss in endothelial cell function. The altered sensitivity to the vasodilators on day 4 suggests that vessels should only be stored for up to three days following dissection for analysis of functional responses.