Local regulation of coronary blood flow may involve an interplay of the vasoactive properties of several metabolic factors. To evaluate the effect of adenosine (Ado) on K+ induced relaxation of vascular smooth muscle, helical strips of cat coronary arteries, suspended in an organ bath of Kreb's solution (37° C, 95% O2 and 5% CO2), were studied during isometric contraction stimulated by acetylcholine (ACh). From a baseline concentration of 3.0 mM, a small increment in [K+] of 2 mM induced a 16.0 ± 2.7% relaxation of tension from the initial level. However, in the presence of Ado, which induced a 20.4 ± 3.0% relaxation of 29.7 ± 4.6%. The latter was significantly greater (P < 0.005) than the response in the absence of Ado. Similarly, a 4 mM [K+] increment elicited a 14.9 ± 3.0% relaxation prior to the addition of Ado, and an enhanced (P < 0.001) response of 29.4 ± 4.4% in the presence of Ado. Thus, the presence of adenosine potentiated the relaxation of ACh stimulated active tension by incremental elevation of [K+]. This finding supports the concept that vasoactive agents may interact to relax arterial smooth muscle, and may have implications regarding local coronary blood flow regulation.
|Original language||English (US)|
|Number of pages||1|
|State||Published - 1975|
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