A whole mounted model for the study of smooth muscle mechanics is described which uses cylindrical sections of middle cerebral artery (MCA). One- to 2-cm sections of artery were cannulated, pressurized and perfused. Changes in the outer diameter of the artery were detected using an infrared photoelectric diameter gauge. MCA displayed spontaneous rhythmic contractions, which were initiated and sensitive to changing intraluminal pressure. Rhythmic activity was dependent upon the presence of Ca2+ in the bath, but not affected by phentolamine. Increasing pressure significantly reduced high (50, 70 and 125 mM) potassium-induced contractions, but not drug (serotonin, norepinephrine, histamine) induced contractions. The intraluminal surface of the MCA was significantly more sensitive to serotonin than the extraluminal surface. The above contractile responses are discussed in light of the advantages of this model over helical or ring preparations.