Abolition of flow-dependent EDRF release before that evoked by agonists in hypercholesterolaemic rabbits

Hutcheson, Iain Robert, Warden-Smith, Jeremy and Griffith, T. M. 1994. Abolition of flow-dependent EDRF release before that evoked by agonists in hypercholesterolaemic rabbits. British Journal of Pharmacology 113 (1) , pp. 190-194.

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Abstract

1. We have used a pulsatile cascade bioassay system to investigate the effects of dietary-induced hypercholesterolaemia on EDRF release evoked by acetylcholine and by the oscillatory and time-averaged components of flow, in isolated segments of rabbit abdominal aorta. 2. Flow pulsatility (frequency range 0.1-10 Hz) was studied with constant flow (9 ml min-1) at a pulse pressure amplitude of 2 mmHg. Frequency-related EDRF release, maximal at 6 Hz, was slightly attenuated after 4 weeks and abolished after 8 weeks of cholesterol feeding. 3. Time-averaged shear stress was manipulated with dextran (1-4% w/v, 80000 mol. wt.), to increase perfusate viscosity. EDRF release induced by increased perfusate viscosity was unaffected after 4 weeks but abolished after 8 weeks of cholesterol feeding. 4. Endothelium-dependent relaxations to acetylcholine (0.1-10 microM) were not influenced after 4 weeks and only partially attenuated (by 60% of the maximal response, EC50 unchanged at 6.45 +/- 0.04 vs. 6.4 +/- 0.1 microM) after 8 weeks of cholesterol feeding. 5. Blood cholesterol levels were significantly (P < 0.001) increased after 4 weeks (26 +/- 3.6 vs 2.6 +/- 0.6 mmol l-1) and 8 weeks (56.2 +/- 3.8 vs 1.3 +/- 0.1 mmol l-1) of cholesterol feeding but after 8 weeks plasma L-arginine levels were not significantly different from the age-matched controls (0.2 +/- 0.05 vs. 0.19 +/- 0.04 mmol l-1). 6. We conclude that hypercholesterolaemia impairs flow-related (pulsatile- and time-averaged shear-induced) EDRF release earlier than acetylcholine-induced relaxation in rabbit aorta. This is consistent with the view that different transduction mechanisms mediate EDRF release in response to agonists and flow.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Business (Including Economics) Medicine
Subjects:	R Medicine > RM Therapeutics. Pharmacology
Publisher:	Wiley-Blackwell
ISSN:	0007-1188
Last Modified:	17 Mar 2021 02:35
URI:	https://orca.cardiff.ac.uk/id/eprint/10876

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