In this study, the effect and effect mechanisms of [Pyr1]apelin-13, the dominant apelin isoform in the human cardiovascular tissues and human plasma, on vascular contractility were investigated. The vascular rings obtained from the thoracic aortas of the male Wistar Albino rats were placed in the isolated tissue bath system. After the equilibration period, [Pyr1]apelin-13 (10-9 to 10-6 M) was applied cumulatively to the aortic rings pre-contracted with phenylephrine in the plateau phase. The protocol was repeated in the presence of specific signaling pathway inhibitors (F13A, L-NAME, dorsomorphin, TEA, U0126, or indomethacin) to determine the effect mechanisms of [Pyr1]apelin-13. [Pyr1]apelin-13 induced a dose-dependent relaxation in the pre-contracted aortic rings. APJ, eNOS, AMPK, and potassium channel inhibition statistically significantly decreased the vasodilator effect of [Pyr1]apelin-13. MAPK and COX inhibition didn't statistically significantly changed the vasodilator effect of [Pyr1]apelin-13. In conclusion, [Pyr1]apelin-13 relaxes the rat thoracic aorta via APJ, NO, AMPK, and potassium channels.