Effects of baroreceptor activation on spontaneous activity in the sweat glands and nictitating membrane of the cat.
(1) In chloralose-anesthetized cats, elevation of carotid sinus pressure caused blood pressure, sweat gland potentials and nictitating membrane tension to decrease. (2) The onset and recovery of the sweat gland and nictitating membrane responses usually preceded the respective phases of the blood pressure (depressor) response; the latencies of the sweat gland and nictitating membrane responses agreed with the latencies predicted for neural reflex pathways. (3) The sweat gland and nictitating membrane responses were evoked less consistently than the depressor response. (4) In experiments where only the sweat gland potentials and blood pressure were studied: (a) the sinus pressure threshold for inhibition of sweat gland activity was similar to the threshold for the depressor response; (b) cutting the sinus nerves, or blocking the efferent neural activity to the sweat glands, eliminated the effects of sinus pressure elevation on the sweat gland potentials; (c) with carotid sinus pressure held constant, decreases in blood pressure, produced by stimulating the peripheral end of the vagus nerve, did not affect the sweat gland potentials. (5) These results indicate that baroreceptors can reflexly modulate activity in sympathetic neurons whose target organs are not fundamentally involved in blood pressure regulation.
D000320:Adrenergic Fibers / Q000502:physiology; D000818:Animals; D001794:Blood Pressure; D002346:Carotid Sinus / Q000294:innervation; D002415:Cats; D005071:Evoked Potentials; D005260:Female; D008297:Male; D009541:Nictitating Membrane / Q000294:innervation*; D011311:Pressoreceptors / Q000502:physiology*; D012018:Reflex / Q000502:physiology; D013545:Sweat Glands / Q000294:innervation*