Vascular response to short-term systemic hypoxia, hypercapnia, and asphyxia in the cat.
Acute systemic hypoxia, hypercapnia, or asphyxia was produced in ketamine-anesthetized, paralyzed cats by ventilating them for 2-4 min with appropriate gas mixtures. A sustained rise in arterial pressure occurred in all cases. Vascular responses to hypoxia (7% O2, 10%  02, or 14% O2) included muscle constriction, cutaneous (hindpaw) dilatation (no change with 14% O2), renal constriction (unchanged flow), and unchanged intestinal resistance. Asphyxia (hypoxia + 10% CO2) produced a similar pattern, except that intestinal dilatation occurred. Hypercapnia (10% CO2 + 21% O2) produced muscle constriction, renal constriction (unchanged flow), intestinal dilatation, and no change in cutaneous resistance. Intestinal dilatation seemed in all cases a response to elevated CO2 only. Hypercapnia augmented the effects of hypoxia in skin and skeletal muscle. The variation of responses in different vascular beds suggests a patterning of sympathetic discharge, and varying responsivity to local and humoral factors.
D000818:Animals; D001237:Asphyxia / Q000503:physiopathology*; D001783:Blood Flow Velocity; D001794:Blood Pressure; D001808:Blood Vessels / Q000503:physiopathology*; D002415:Cats; D005260:Female; D006439:Hemodynamics; D006614:Hindlimb / Q000098:blood supply; D006935:Hypercapnia / Q000503:physiopathology*; D000860:Hypoxia / Q000503:physiopathology*; D007422:Intestines / Q000098:blood supply; D007668:Kidney / Q000098:blood supply; D008297:Male; D009132:Muscles / Q000098:blood supply; D012039:Regional Blood Flow; D012867:Skin / Q000098:blood supply; D014666:Vasomotor System / Q000503:physiopathology*