Interactions between K+ and beta 2-adrenoreceptors in determining muscle vasodilatation induced in the rat by systemic hypoxia.
In spontaneously breathing anaesthetized rats, both moderate and severe hypoxia caused increases in [K+] in venous efflux from hindlimb muscle, from 4.3 to 4.6 and from 3.8 to 4.4 mM respectively; the increases were accentuated to 5.2 and 5.7 mM after beta 2-receptor blockade with I.V. sotalol. Sotalol also potentiated the vasodilatation evoked in hindlimb muscle by moderate hypoxia, but reduced that evoked by severe hypoxia. We propose that K+ released from muscle during hypoxia contributed to the local vasodilatation. Further, we suggest that this effect was enhanced in moderate hypoxia by blockade of the beta 2-mediated uptake mechanism for K+ in skeletal muscle, but outweighed in severe hypoxia by blockade of the beta 2-mediated dilator action of circulating catecholamines on vascular muscle.
Mian
R
R
Department of Physiology, Medical School, Birmingham.
Marshall
J M
JM
Kumar
P
P
D000818:Animals; D001784:Blood Gas Analysis; D001916:Brachial Artery / Q000502:physiology; D005263:Femoral Artery / Q000502:physiology; D000860:Hypoxia; D009132:Muscles / Q000098:blood supply* / Q000378:metabolism; D010100:Oxygen; D011188:Potassium / Q000378:metabolism*; D051381:Rats; D011943:Receptors, Adrenergic, beta / Q000378:metabolism*; D013015:Sotalol; D014664:Vasodilation / Q000502:physiology*
D011943:Receptors, Adrenergic, beta; D013015:Sotalol; D011188:Potassium; D010100:Oxygen