Effects of selective ETB‐receptor stimulation on arterial, venous and capillary functions in cat skeletal muscle
Why the study?
Do selective ETB-receptor agonists affect vascular resistance and capillary function in cat skeletal muscle?
Population
Sympathectomized cat skeletal muscle (in vivo) and cat femoral artery and vein (in vitro)
Design
Preclinical
Authors
Discussion
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Member takes
Implication
ETB agonism elicits biphasic arteriolar responses in feline muscle; leaves open effects on human vascular resistance or capillary function.
Key Points
- To characterize and quantify the in vivo and in vitro effects of selective endothelin B receptor stimulation across arterial, capillary, and venous segments in cat skeletal muscle.
- Infused selective ETB-receptor agonists (IRL 1620 and BQ 3020) intra-arterially into sympathectomized cat skeletal muscle preparations to measure segmental vascular tone, capillary pressure, and fluid exchange.
- Administered pharmacological blockers—including L-NAME for nitric oxide, FR139317 for ETA receptors, and indomethacin for prostacyclin—to identify mediating mechanisms.
- Tested isolated cat femoral arteries and veins in vitro to determine direct vessel responses to IRL 1620.
- Intra-arterial ETB-agonist infusion elicited an initial transient dilation followed by moderate dose-dependent constriction, with both effects localized preferentially to small arterioles (< 25 μm).
- Arteriolar dilation transiently increased capillary pressure, whereas subsequent constriction decreased capillary pressure and reduced the capillary filtration coefficient, causing net fluid absorption.
- Prostacyclin inhibition with indomethacin reduced dilator amplitude and accelerated vasoconstriction onset, while nitric oxide and ETA-receptor blockades produced no observable effects in vivo.
Structured PICO
Do selective ETB-receptor agonists affect vascular resistance and capillary function in cat skeletal muscle?
P
Population
Sympathectomized cat skeletal muscle (in vivo) and cat femoral artery and vein (in vitro)
I
Intervention
Selective ETB-receptor agonists (IRL 1620 and BQ 3020) infused intra-arterially
O
Outcome
Vascular resistance (tone) in large-bore arterial resistance vessels, small arterioles, and veins, and capillary pressure/transcapillary fluid exchangesurrogate
ETB-receptor stimulation mediates both dilator and constrictor responses to endothelins in cat skeletal muscle in vivo.
Cite This Study
Ekelund et al. (1994) studied this question.