Functional and compositional studies of arteries stored in University of Wisconsin solution compared with Krebs-Bülbring buffer

Structure and Function of Porcine Arteries Are Preserved for up to 6 Days Using the HypoRP Cold-storage Solution

BACKGROUND

Maintaining functional vessels during preservation of vascularized composite allografts (VCAs) remains a major challenge. The University of Wisconsin (UW) solution has demonstrated significant short-term benefits (4-6 h). Here we determined whether the new hypothermic resuscitation and preservation solution HypoRP improves both structure, survival, and function of pig arteries during storage for up to 6 days.

METHODS

Using porcine swine mesenteric arteries, the effects of up to 6-day incubation in a saline (PBS), UW, or HypoRP solution on the structure, cell viability, metabolism, and function were determined.

RESULTS

After incubation at 4°C, for up to 6 days, the structures of the arteries were significantly disrupted, especially the tunica media, following incubation in PBS, in contrast with incubation in the HypoRP solution and to a lesser extent, in UW solution. Those disruptions were associated with increased active caspase 3 indicative of apoptosis. Additionally, while incubation in PBS led to a significant decrease in the metabolic activity, UW and HypoRP solutions allowed a stable to increased metabolic activity following 6 days of cold storage. Functional responsiveness to phenylephrine (PE) and sodium nitroprusside (SNP) decreased over time for artery rings stored in PBS and UW solution but not for those stored in HypoRP solution. Moreover, artery rings cold-stored in HypoRP solution were more sensitive to ATP.

CONCLUSIONS

The HypoRP solution improved long-term cold storage of porcine arteries by limiting structural alterations, including the collagen matrix, reducing apoptosis, and maintaining artery contraction-relaxation functions for up to 6 days.

Alterations in the mechanical properties of bladder smooth muscle in hydrocephalus rat model

OBJECTIVES

It is now well established that hydrocephalus is associated with impaired bladder function. The aim of this study was to determine the effects of hydrocephalus on bladder smooth muscle (BSM) reactivity in the rat model.

MATERIALS AND METHODS

Hydrocephalus was induced in 7-day-old rats by injection of kaolin into the cisterna magna (AH group). Control group rats underwent a sham operation. After 10 days, rats were decapitated. Each bladder was excised and BSM strips placed in an organ bath where contractile and relaxant responses were studied.

RESULTS

Contractile response of BSM to KCl decreased in the AH group. Increased response to muscarinic agonist carbachol was observed in the AH group. The relaxant response to adrenergic agonist isoprenaline was significantly decreased in the AH group, whereas non-receptor-dependent agonist papaverine was unchanged in 2 groups.

CONCLUSION

Bladder smooth muscle reactivity is affected by the formation of hydrocephalus essentially by both receptor-dependent and non-receptor-dependent mechanisms. This pathway may be a novel target for the pharmacologic treatment of bladder dysfunction secondary to hydrocephalus.

Effects of cold storage on the function and morphology of isolated urinary bladder in rat

AIMS

We investigated the effects of 24- and 48-hr storage at 4 degrees C in Krebs solution on the function and morphology of isolated, rat urinary bladders.

METHODS

Strips of bladder were obtained from eight male Sprague-Dawley rats. Six strips were harvested from each bladder and randomized to storage for 24 or 48 hr at 4 degrees C in Krebs solution or examination immediately after harvest. Contractile responses of the strips to potassium chloride (KCl), electric field stimulation (EFS), adenosine 5'-triphosphate (ATP) and carbamylcholine (CCh) were assessed. Histological examination of the bladder strips was performed. The pO(2), pCO(2), and pH of the solution in each storage container were measured at each storage time point.

RESULTS

Cold storage induced a significant decrease in the amplitude of contraction in response to KCl and EFS after 24 or 48 hr of storage compared with control. The response of the bladder strips to ATP and CCh was significantly reduced after 48-hr storage compared with control, but not 24-hr storage. The pO(2) and pCO(2) decreased after cold storage. The pH increased after 24 hr of storage and remained stable between 24 and 48 hr of storage. Histological evaluation of the strips showed tissue swelling after 24 and 48 hr of storage.

CONCLUSIONS

These results suggest that the morphology and function of bladder strips stored for 24 to 48 hr at 4 degrees C in Krebs solution undergo significant changes. Further studies are needed to assess the allowable time for storage of bladder tissue.

The action of nitric oxide on hepatic haemodynamics during secondary biliary cirrhosis in the rat

The role of nitric oxide (NO) in portal hypertension is poorly understood. The role of NO upon hepatic arterial and portal venous vasoconstrictor responses to noradrenaline and ATP in rats with secondary biliary cirrhosis was evaluated. Cirrhosis was induced by bile duct ligation after which livers were excised and dual-perfused in vitro. Concentration-dependent dose-response curves were then constructed to hepatic arterial and portal venous noradrenaline and ATP. Hepatic arterial responses to noradrenaline and ATP were significantly attenuated in cirrhotic rats. 100 microM N(G)-nitro-L-arginine methyl ester (L-NAME) restored attenuated hepatic arterial responses to noradrenaline and ATP in cirrhotic rats. Portal venous responses to noradrenaline in cirrhotic rats were significantly increased compared to controls and were not affected by L-NAME. However, portal venous responses to ATP were significantly attenuated in cirrhotic rats and were also not restored by L-NAME. Hepatic arterial or portal venous responses to noradrenaline did not change after infusion of L-NAME. Hepatic arterial responses to noradrenaline and ATP were significantly attenuated in cirrhotic rats, possibly due to increased production of NO. However, portal venous responses in cirrhotic rats were increased to noradrenaline and attenuated to ATP, and were not related to increased NO production.

Cold storage of rabbit thoracic aorta in University of Wisconsin solution attenuates P2Y(2) purine receptors

Post-transplantation thrombosis may occur in donor segments of iliac arteries and livers following surgical removal and storage in University of Wisconsin (UW) solution for transplantation. We have previously suggested that purine receptors are vulnerable to denaturation after UW storage. The aims of the present study were to determine what particular subtypes of purine P2Y receptors in rabbit thoracic aorta deteriorate after 8 days of UW storage by studying vascular reactivity to acetylcholine, ATP, 2MeSATP and UTP. Ring segments of aortae from male New Zealand White rabbits were mounted upon fine-wire myographs and vasodilatation to the above agents tested on fresh tissue, and after 8 days of UW storage. Vasodilatation to ATP was attenuated by 100 microM L-NAME in fresh tissue suggesting that the relaxant response was, in part, due to nitric oxide (NO). P2Y-mediated relaxation to ATP was significantly attenuated by UW storage and cholinergic responses were not. This attenuated relaxation to ATP was not further attenuated by L-NAME, suggesting a loss of the NO-dependent mechanism. De-endothelialisation indicated that UTP-mediated vasorelaxation, via P2Y(2) receptors, was endothelium-dependent. Any residual endothelium-independent relaxation to UTP was abolished by UW storage and endothelium-dependent UTP relaxation was reduced to the same level as that seen in fresh, de-endothelialised tissue. In contrast responses to 2MeSATP, via P2Y(1) receptors, were predominantly endothelium-independent and were only partially attenuated by UW storage. Responses to pyridoxalphosphate-6-azophenyl-2('),4(')-disulphonic acid (PPADS) and L-NAME suggested that vasorelaxation to 2MeSATP and UTP was mediated by P2Y(1) and P2Y(2) receptors, respectively. It is therefore concluded that UW storage predominantly decreases P2Y(2) receptor-mediated vascular reactivity.