Induction and Registration of Changes in Arteriolar Vasomotor Tone in Vivo
Description of a Method
1994 年 5 巻 4 号 p. 262-274
詳細
1994 年 5 巻 4 号 p. 262-274
A technique is described for the induction and registration of changes in vasomotor tone in mesenteric arterioles of the guinea pig. Through a platinum electrode, insulated except at the tip and positioned at a fixed distance from the selected arteriolar segment, a negative direct current (1μA) applied for 20 seconds induced a vasoconstriction followed by relaxation within three minutes. If experimental conditions remained unchanged, arteriolar constriction could be induced every 4 minutes, repeated 10 times in succession, and with almost identical changes in vasomotor tone. Quantification was performed on video recordings of the investigated arteriolar segment by measuring the intraluminal diameter directly from the image on the monitor screen. Visual inspection, confirmed by statistical analysis, demonstrated that the constriction-relaxation phenomena of the arteriole were fully reproducible at the site directly opposite the electrode. In the applied experimental protocol, the arteriole served as its own control for evaluation of the effect of drug administration. Phentolamine as well as carbacyclin, although affecting vasomotricity through different mechanisms, both significantly decreased the standardised constrictive responses. Our findings clearly indicate that other drugs and/or mediators deserve investigation by this method in order to unravel their vasoactive properties in in vivo conditions.
