Influence of substance P on carotid sinus nerve baro- and chemoreceptor activity in rabbits.

Title

Influence of substance P on carotid sinus nerve baro- and chemoreceptor activity in rabbits.

Creator

Qu L; Stuesse S L

Publisher

Peptides

Date

1990
1990-10

Description

Substance P (SP) is abundant in the carotid sinus nerve (CSN) and has been implicated in baro- and chemoreceptor reflexes. We examined the effect of SP on blood pressure, heart rate, phrenic nerve activity, hindlimb perfusion pressure, and cardiac contractile strength in urethane-anesthetized rabbits with bilaterally cut cervical sympathetic, vagus, and aortic depressor nerves. Retrograde simultaneous injection of SP (0.5-2.7 micrograms/kg in 0.2-0.3 ml saline) into both carotid sinus areas via the internal carotid arteries decreased blood pressure (by 56%), heart rate (by 13%), cardiac contractility (by 25%) and phrenic nerve activity (by 77%). The effect on hindlimb perfusion pressure was variable. There was both a reflex effect and direct hindlimb vasodilation. In another group of rabbits, the carotid sinus areas were vascularly isolated and perfused with SP (0.19 micrograms/min dissolved in Locke's solution) or Locke's solution alone for 5 min. While carotid sinus perfusion pressure was maintained in the range of 80-120 mmHg, mean arterial blood pressure, heart rate, and unit activity from the CSN were recorded. SP increased the activity of 11 of 18 baroreceptor fibers and inhibited all of 20 chemoreceptor fibers. SP decreased mean arterial blood pressure and heart rate, but the changes were less than those obtained with injection of SP into nonisolated carotid sinus arteries because systemic effects of SP, which in some cases counteracted the reflex effects, were eliminated.

Subject

Female; Male; Animals; Rabbits; Myocardial Contraction/drug effects; Hemodynamics/drug effects; Blood Pressure/*drug effects; Carotid Sinus/*innervation; Chemoreceptor Cells/*drug effects; Hindlimb/blood supply; Phrenic Nerve/drug effects; Pressoreceptors/*drug effects; Substance P/*pharmacology

Rights

Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).

Pages

955–961

Issue

5

Volume

11

Citation

Qu L; Stuesse S L, “Influence of substance P on carotid sinus nerve baro- and chemoreceptor activity in rabbits.,” NEOMED Bibliography Database, accessed December 7, 2021, https://neomed.omeka.net/items/show/5584.

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