Abstract
AIM: The aim of the present study was to examine the role of Ca2+-mediated contractile responses in isolated mesenteric resistance arteries from rats with congestive heart failure (CHF).
METHODS: Heart failure was induced by ligation of the left coronary artery. Rats exposed to the same surgical procedure except ligation served as controls (Sham). The following experiments were conducted: (1) passive increase in radial stretch (the length-tension relationship) in Ca2+-free and in depolarizing high K+-solution; (2) the contractile responses to external application of Ca2+ and high K+-solutions in the presence of nifedipine and phentolamine; and (3) a histological evaluation of CHF and Sham vessels.
RESULTS: The length-tension induced response in Ca2+-free buffer solution was significantly lower in arteries from CHF rats, starting at a very low tension (0.9+/-0.2 mN/mm for heart failure and 1.7+/-0.2 mN/mm for Sham). This difference, but at a higher degree of stretch, was also present in K+-activated vessels. The external application of Ca2+ in K+-depolarized vascular segments in the presence of phentolamine (1 microM) induced an enhanced contractile response in arteries from CHF rats compared with Sham (4.8+/-0.3 mN/mm and 3.6+/-0.6 mN/mm, respectively, P=0.059). In the absence of phentolamine the reverse response was found (4.0+/-0.4 mN/mm and 5.7+/-0.3 mN/mm for CHF vs. Sham respectively, P=0.035). Application of increasing concentrations of K+-solution induced a stronger contractile response in Sham compared with CHF arteries (Sham 4.9+/-0.4 and heart failure 4.0+/-0.3, P=0.04). Microscopic examination of vessels yielded no difference in gross morphology, media thickness or wall to lumen ratio between CHF and Sham arteries.
CONCLUSION: The results indicate an attenuation of alpha-adrenoceptors and a difference of Ca2+-mediated vascular contractility in resistance arteries of congestive heart failure rats.
Originalsprog | Engelsk |
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Tidsskrift | European Journal of Heart Failure |
Vol/bind | 3 |
Udgave nummer | 1 |
Sider (fra-til) | 7-13 |
Antal sider | 7 |
ISSN | 1388-9842 |
Status | Udgivet - jan. 2001 |
Udgivet eksternt | Ja |