Division of Clinical Pharmacology, Department of General Internal Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland.
Institute of Pharmacology, University of Bern, Bern, Switzerland.
Am J Hypertens. 2018 Jan 12;31(2):188-196. doi: 10.1093/ajh/hpx163.
The right atrium is densely innervated and provides sensory input to important cardiocirculatory reflexes controlling cardiac output and blood pressure. Its angiotensin (Ang) II-expressing innervation may release Ang II as a neuropeptide cotransmitter to modulate reflexes but has not yet been characterized.
Intraoperative surgical biopsies from human right atria (n = 7) were immunocytologically stained for Ang II, tyrosine hydroxylase (TH), and synaptophysin (SYN). Tissue angiotensins were extracted and quantified by radioimmunoassay.
Angiotensinergic fibers were frequent in epicardial nerves and around vessels with variable TH co-localization (none to >50%/bundle). Fibers were also widely distributed between cardiomyocytes and in the endocardium where they were typically nonvaricose, TH/SYN-negative and usually accompanied by varicose catecholaminergic fibers. In the endocardium, some showed large varicosities and were partially TH or SYN-positive. A few endocardial regions showed scattered nonvaricose Ang fibers ending directly between endothelial cells. Occasional clusters of thin varicose terminals co-localizing SYN or TH were located underneath, or protruded into, the endothelium. Endocardial density of Ang and TH-positive fibers was 30-300 vs. 200-450/mm2. Atrial Ang II, III, and I concentrations were 67, 16, and 5 fmol/g (median) while Ang IV and V were mostly undetectable.
The human right atrium harbors an abundant angiotensinergic innervation and a novel potential source of atrial Ang II. Most peripheral fibers were noncatecholaminergic afferents or preterminal vagal efferents and a minority was presumably sympathetic. Neuronal Ang II release from these fibers may modulate cardiac and circulatory reflexes independently from plasma and tissue Ang II sources.
右心房密布神经，为控制心输出量和血压的重要心循环反射提供感觉输入。其血管紧张素（Ang）II 表达的神经支配可能会释放 Ang II 作为神经肽共递质来调节反射，但尚未得到描述。
对来自人类右心房的术中手术活检标本（n = 7）进行免疫细胞化学染色，以检测 Ang II、酪氨酸羟化酶（TH）和突触小体（SYN）。通过放射免疫分析法提取和定量组织中的血管紧张素。
在心脏外膜神经和血管周围存在丰富的血管紧张素能纤维，其 TH 共定位存在差异（无到 >50%/束）。纤维也广泛分布在心肌细胞之间，在心内膜中，这些纤维通常无曲张，TH/SYN 阴性，通常伴有曲张的儿茶酚胺能纤维。在心内膜中，一些纤维显示出大的曲张，部分 TH 或 SYN 阳性。一些心内膜区域显示出散在的非曲张 Ang 纤维，直接终止于内皮细胞之间。偶尔会出现一些簇状薄的曲张终末，与 SYN 或 TH 共定位，位于内皮细胞下方或突出于内皮细胞。心内膜 Ang 和 TH 阳性纤维的密度分别为 30-300 个/mm2 和 200-450 个/mm2。心房 Ang II、III 和 I 的浓度分别为 67、16 和 5 fmol/g（中位数），而 Ang IV 和 V 则大多无法检测到。
人类右心房拥有丰富的血管紧张素能神经支配和心房 Ang II 的新潜在来源。大多数周围纤维是非儿茶酚胺能传入纤维或节前迷走传出纤维，少数可能是交感神经纤维。这些纤维中的神经元 Ang II 释放可能独立于血浆和组织 Ang II 来源来调节心脏和循环反射。
