Exosomes are the smallest-sized (50-150 nm in diameter) extracellular vesicles enclosed by a lipid-bilayer with density of 1.12-1.19 g ml-1. Exosomes are considered to mediate cell-cell communication, since they contain various molecules, including protein and microRNA. We previously reported that plasma-derived exosomes partly regulate systemic blood pressure in both normotensive and hypertensive rats, suggesting that exosomes could affect vascular reactivity. We thus examined the effects of exosomes derived from cultured media of organs (brain, heart, liver and kidney) isolated from spontaneously hypertensive rats (SHR, 5-week-old) on reactivity of isolated thoracic aorta from normal Wistar rats (6-9-week-old). In endothelium-intact thoracic aorta, pretreatment with exosomes for 10 min and 2 h had no big effect on contraction induced by noradrenalin. The exosomes had also no big influence on acetylcholine-induced endothelium-dependent relaxation. Further study is required to elucidate whether hypertensive animal-derived exosomes could affect vasoreactivity.