Rioux F, Bachelard H, Bernoussi A, St-Pierre S
Department of Pharmacology, Faculty of Medecine, Laval University, Ste-Foy, QC Canada.
Peptides. 1988 Jul-Aug;9(4):883-92. doi: 10.1016/0196-9781(88)90137-4.
We tested the influence of capsaicin (CAP) desensitization on the positive chronotropic and inotropic effects of neurotensin (NT), bradykinin (BK), calcitonin gene-related peptide (CGRP) and noradrenaline (NA) in guinea pig isolated atria. The positive chronotropic and inotropic effects of NT and BK were completely inhibited, whereas those elicited by CGRP and NA were either slightly reduced (CGRP) or unaffected (NA), in CAP-desensitized compared to control atria. Cross-desensitization studies using CAP, NT and BK showed that the positive chronotropic and inotropic effects of CAP are slightly affected, whereas those evoked by BK are markedly reduced in NT-desensitized atria. On the other hand, the positive chronotropic and inotropic effects of CAP and NT were similar in BK-desensitized and control atria. The results were interpreted as an indication that NT, BK and CAP produce their excitatory effects in guinea pig atria by interacting with a common population of CAP-sensitive sensory nerve fibers (presumably substance P (SP)- and CGRP-containing nerve fibers). The absence of cross-desensitization between NT or BK and CAP, or between NT and BK, suggests that the activation and desensitization of atrial, CAP-sensitive sensory nerve fibers by the latter agents involve different receptors and/or mechanisms.
我们测试了辣椒素（CAP）脱敏对豚鼠离体心房中神经降压素（NT）、缓激肽（BK）、降钙素基因相关肽（CGRP）和去甲肾上腺素（NA）的正性变时和变力作用的影响。与对照心房相比，在CAP脱敏的心房中，NT和BK的正性变时和变力作用被完全抑制，而CGRP和NA引起的作用要么略有降低（CGRP），要么不受影响（NA）。使用CAP、NT和BK进行的交叉脱敏研究表明，CAP的正性变时和变力作用受到轻微影响，而在NT脱敏的心房中，BK引起的作用则明显降低。另一方面，在BK脱敏的心房和对照心房中，CAP和NT的正性变时和变力作用相似。这些结果被解释为表明NT、BK和CAP通过与一群共同的CAP敏感感觉神经纤维（可能是含P物质（SP）和CGRP的神经纤维）相互作用，在豚鼠心房中产生兴奋作用。NT或BK与CAP之间，或NT与BK之间不存在交叉脱敏，这表明后一种药物对心房CAP敏感感觉神经纤维的激活和脱敏涉及不同的受体和/或机制。
