Alpha-adrenergic vasoconstriction in arterial and arteriolar sections of the canine coronary circulation

摘要: Using a method which allowed the in-situ measurement of segmental coronary vascular resistances, reaction arterial and arteriolar sections system to α-receptor stimulation was studied in anaesthetized dogs. The left artery cannulated, perfusion pressure kept constant. Allowance made for extravascular metabolic influences α-stimulation on resistances. On an average, submaximal with xylometazoline increased resistance by about 60% 90%. cannulation sympathetic reactivity arterioles. Moreover, component 4%. Thus it can be assumed that under normal in-vivo conditions vasoconstriction might less different arteries Since ranges from 20% 50% total resistance, this section lead even critical limitation blood flow. other hand, predominant constriction arterioles leads increase peripheral pressure, i.e. “reverse steal phenomenon”.