Ursell P C, Mayes M
Department of Pathology, University of California at San Francisco 94143-0506.
Cardiovasc Res. 1993 Nov;27(11):1920-4. doi: 10.1093/cvr/27.11.1920.
As a physiological mediator of smooth muscle relaxation and possibly a non-adrenergic non-cholinergic (NANC) neurotransmitter, nitric oxide plays a role in regulating coronary artery blood flow and modulating myocardial contractility. Although recent attention has been directed toward neural tissue, we investigated the possibility that vessels, as well as nerves, may be a source of nitric oxide in the heart.
The NADPH-diaphorase method was used to localise the synthesis enzyme, nitric oxide synthase (NOS), in the pig heart.
All regions showed a similar staining pattern. Muscle fibres had virtually no NOS activity. The endocardium showed reaction product in a lattice configuration without much cytoplasmic staining, suggesting that endothelial cell membranes are the primary site of NOS activity. Every vessel contained reaction product in intima but none in the media or adventitia. Muscular arteries had more NOS activity than veins. Lighter staining capillaries coursed along each muscle fibre. Only a few scattered nerve processes and rare neuronal cell bodies with NOS activity were present in the heart; there was no particular spatial relationship between neural tissue and vessels.
(1) the majority of NOS activity in the pig heart is in vascular endothelium, consistent with the concept of nitric oxide as a regulator of coronary blood flow; less is present in the endocardium; (2) paucity of nerves with NOS activity probably indicates that this particular type of NANC neural tissue does not affect coronary blood flow directly; and (3) although muscle fibres have no discernible NOS activity, the rich vascular supply in close proximity may subserve some myocardial function of nitric oxide.
作为平滑肌舒张的生理介质，并且可能作为一种非肾上腺素能非胆碱能（NANC）神经递质，一氧化氮在调节冠状动脉血流和心肌收缩力方面发挥作用。尽管最近的研究重点已转向神经组织，但我们研究了血管以及神经可能是心脏中一氧化氮来源的可能性。
采用NADPH黄递酶法对猪心脏中的合成酶一氧化氮合酶（NOS）进行定位。
所有区域均呈现相似的染色模式。肌纤维几乎没有NOS活性。心内膜呈网格状反应产物，细胞质染色不多，提示内皮细胞膜是NOS活性的主要部位。每条血管的内膜均有反应产物，而中膜和外膜均无。肌性动脉的NOS活性高于静脉。浅色染色的毛细血管沿每条肌纤维走行。心脏中仅存在少数散在的有NOS活性的神经突起和罕见的神经元细胞体；神经组织与血管之间没有特定的空间关系。
（1）猪心脏中大部分NOS活性存在于血管内皮，这与一氧化氮作为冠状动脉血流调节因子的概念一致；心内膜中的活性较少；（2）具有NOS活性的神经稀少可能表明这种特殊类型的NANC神经组织不会直接影响冠状动脉血流；（3）尽管肌纤维没有可辨别的NOS活性，但紧邻的丰富血管供应可能有助于一氧化氮发挥某些心肌功能。
