Increased receptor expression supports vascular reactivity of the rabbit aorta during preservation

Abstract

OBJECTIVES The mechanistic understanding of vascular functional impairment during preservation time helps determine the optimal time frame in which explanted arteries can be used. The method of choice is to measure vascular reactivity and receptor expression. Our goal was to study the influence of preservation for 24 and 48 h on vascular reactivity and receptor expression in rabbit aorta. METHODS Aortic rings preserved in Krebs–Henseleit solution were evaluated fresh (t0), 24 h (t24) and 48 h (t48) after harvest for (i) vascular reactivity as sensitivity (pD2) and maximum effect in response to potassium chloride, U46619 (thromboxane-A2 agonist), phenylephrine, carbachol and isoproterenol, in an organ bath; and for (ii) expression of α1, β2 and thromboxane-prostanoid receptors, by immunofluorescence. RESULTS Compared to the control, after 24 h of preservation, potassium chloride-induced pD2 increased a significant 3.6%, whereas U46619-induced vasoconstriction decreased 9%. None of the agonists affected vasodilation. Intimal and medial α1 receptor expression increased 2.5-fold. After 48 h of preservation, α1 expression and vasoconstrictor responses remained similar to those after 24 h of preservation, but in vasodilation the carbachol-induced maximum effect decreased 30% whereas isoproterenol-induced pD2 increased 4% and the maximum effect increased 10%. TP and β2 expression in the intima and media increased 1.8- and 2.5-fold, respectively. CONCLUSIONS Up to 48 h of preservation, the adrenergic pathway and its receptors support vasoconstriction and vasodilation, despite a significant deterioration in the prostanoid pathway.

In vitro, ex vivo and in vivo antihypertensive evaluation of enzymatic hydrolysates of Californian red worm (Eisenia fetida) proteins

“…Excess perivascular tissue was removed from the aortic segment under a stereoscope and was then cut into 3–5 mm rings. The rings were used for relaxation and contraction experiments within the first hour after euthanasia [ 32 , 33 ]. The rings were placed in a PanLab LE 13206-organ bath (Barcelona, Spain) with 10 mL of KH solution at 37 °C and were bubbled with carbogen.…”

“…Relaxation studies were performed after inducing contraction with 1 μM PE. Concentration-response curves were generated by exposing aortic rings with endothelium (intact), without endothelium (denuded), or with endothelial blockage (using L-NAME 100 μM) to cumulative concentrations of LP (0.1–1000 μM) [ 32 , 33 ].…”

“…The hypotensive effect was evaluated with the E. fetida hydrolysate, which was administered orally with a feeding tube at concentrations of 75 mg/kg and 150 mg/kg. Dose selection was based on Fu et al, 2020 [ 32 ] and preliminary experiments. The animals' blood pressure and heart rate were measured indirectly with a CODA tail blood pressure monitor (Kent Scientific, USA).…”

“…Subsequently, L-NAME (50 mg/kg/day) was administered for one week to induce hypertension. Next, captopril (5 mg/kg) was administered as a positive control, and the E. fetida hydrolysate was administered as the trial antihypertensive drug at two concentrations (75 and 150 mg/kg) every 48 h. Dose selection was based on Fu et al, 2020 [ 32 ] and preliminary experiments. We measured the blood pressure by placing the device on the animals’ tails and after insufflating the device.…”