Key result
Perivascular adipose tissue significantly attenuated the maximal contractile response of the human radial artery to serotonin compared to skeletonized segments (76.1 vs 108.3 mN).
Why the study?
PVAT surrounding the human internal thoracic artery exhibits anticontractile properties, but whether perivascular tissue of the human radial artery exhibits similar properties to help prevent spasm was unknown.
Does perivascular adipose tissue reduce contractile response and induce vasorelaxation in isolated human radial artery segments?
Does perivascular adipose tissue reduce contractile response and induce vasorelaxation in isolated human radial artery segments?
Absolute Event Rate: 76.1% vs 108.3%
p-value: p=<0.0001
Perivascular adipose tissue of the human radial artery exhibits anticontractile and vasorelaxant properties mediated by an adipocyte-derived relaxing factor that acts independently of the endothelium and potassium channels.
May support PVAT preservation in radial grafts; leaves open effects on patency.
OBJECTIVES: Perivascular adipose tissue (PVAT) surrounding the human internal thoracic artery exhibits anticontractile and vasorelaxing properties associated with the adipocyte-derived relaxing factor (ADRF). The goal of our study was to assess if perivascular tissue of the human radial artery (RA) also exhibits such anticontractile/vasorelaxant properties. It could be especially relevant in preventing RA spasms. METHODS: The study was performed on isolated segments of human pedicled RA. Its skeletonized fragments were suspended on stainless steel wire hooks and gradually contracted with serotonin to establish the concentration-effect relationship in the presence/absence of PVAT. Skeletonized arterial segments were precontracted with a single dose of 10-6 M serotonin (EC80). The 5-ml PVAT aliquots (from PVAT incubated in Krebs-Henseleit solution) were transferred to the RA tissue bath resulting in its relaxation. Subsequently, we investigated if ADRF is dependent on endothelial vasorelaxants (nitric oxide and prostacyclin). We attempted to find the potassium channel responsible for mediating the activity of ADRF using different potassium channel blockers. RESULTS: RA without PVAT contracted more strongly in response to serotonin compared to RA with PVAT [Emax: 108.3 (20.2) vs 76.1 (13.5) mN]. The PVAT aliquot relaxed precontracted RA rings at 43% (2.4%) [72.2 (15.6) to 41.0 (5.6) mN]. ADRF is independent of endothelial vasorelaxants; hence, the addition of NG-monomethyl-l-arginine and indomethacin did not change the vasorelaxant response. Neither of the potassium channel blockers participated in the activity of ADRF. CONCLUSIONS: PVAT of human RA exhibits anticontractile/vasorelaxant properties that are inherently associated with ADRF secretion. We confirmed the endothelial-independent mechanism of the activity of ADRF. However, we failed to find the potassium channel responsible for the action of ADRF.
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Kociszewska et al. (2022) studied Stable coronary artery disease (n=93). Perivascular adipose tissue (PVAT) vs. Skeletonized radial artery without PVAT was evaluated on Maximal contraction (Emax) in response to serotonin (p=<0.0001). Perivascular adipose tissue significantly attenuated the maximal contractile response of the human radial artery to serotonin compared to skeletonized segments (76.1 vs 108.3 mN).
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