Effects of cardiac administration of bradykinin on thoracic spinal neurons in the cat
1982; Elsevier BV; Volume: 78; Issue: 3 Linguagem: Inglês
10.1016/0014-4886(82)90085-1
ISSN1090-2430
AutoresR. Neal Weber, Robert W. Blair, Robert D. Foreman,
Tópico(s)Neuropeptides and Animal Physiology
ResumoAbstract Extracellular action potentials were recorded from single cells located in gray matter of the T2 to T4 spinal segments in chloralose-anesthetized cats. Bradykinin either was injected indirectly into the coronary circulation and the heart via a cannula placed in the left atrium or was applied directly to the epicardium. Bradykinin excited 26 of 56 cells after a latency of 11 ± 1 s and inhibited two cells. Ten of eighteen cells demonstrated tachyphylaxis to repeated injections of bradykinin; the other eight cells were excited similarly to successive injections. All cells in this study received visceral and somatic inputs and were found in laminae I through VIII with a majority located in laminae V and VII. A noxious pinch applied to the somatic receptive fields was required to excite 94% of the cells (high-threshold cells), and hair movement and touch as well as pinch excited the other 6% of the cells (wide dynamic range cells). The results demonstrated that bradykinin excited cardiac receptors whose afferent fibers influenced the activity of spinal neurons. Because convergence of visceral and somatic inputs onto the same neurons provides a basis for referred pain and bradykinin is an algesic substance, these cells could potentially be involved in pain sensation and cardiovascular adjustments associated with angina pectoris.
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