title: Hyperpolarization-activated cyclic nucleotide-gated channels in peripheral diaphragmatic lymphatics.
abstract: Diaphragmatic lymphatic function is mainly sustained by pressure changes in the tissue and serosal cavities during cardiorespiratory cycles. The most peripheral diaphragmatic lymphatics are equipped with muscle cells (LMCs), which exhibit spontaneous contraction, whose molecular machinery is still undetermined. Hypothesizing that spontaneous contraction might involve hyperpolarization-activated cyclic nucleotide-gated (HCN) channels in lymphatic LMCs, diaphragmatic specimens, including spontaneously contracting lymphatics, were excised from 33 anesthetized rats, moved to a perfusion chamber containing HEPES-Tyrode's solution, and treated with HCN channels inhibitors cesium chloride (CsCl), ivabradine, and ZD-7288. Compared with control, exposure to 10 mM CsCl reduced (-65%, n = 13, P < 0.01) the contraction frequency (FL) and increased end-diastolic diameter (DL-d, +7.3%, P < 0.01) without changes in end-systolic diameter (DL-s). Ivabradine (300 μM) abolished contraction and increased DL-d(-14%, n = 10, P < 0.01) or caused an incomplete inhibition of FL(n = 3, P < 0.01), leaving DL-dand DL-sunaltered. ZD-7288 (200 μM) completely (n = 12, P < 0.01) abolished FL, while DL-ddecreased to 90.9 ± 2.7% of control. HCN gene expression and immunostaining confirmed the presence of HCN1-4 channel isoforms, likely arranged in different configurations, in LMCs. Hence, all together, data suggest that HCN channels might play an important role in affecting contraction frequency of LMCs.
authors: Department of Surgical and Morphological Sciences, University of Insubria, Varese, Italy and; daniela.negrini@uninsubria.it.
authors: Daniela
authors: D
authors: Negrini
authors: Department of Surgical and Morphological Sciences, University of Insubria, Varese, Italy and.
authors: Cristiana
authors: C
authors: Marcozzi
authors: Department of Surgical and Morphological Sciences, University of Insubria, Varese, Italy and.
authors: Eleonora
authors: E
authors: Solari
authors: Department of Biotechnology and Life Sciences, University of Insubria, Varese, Italy.
authors: Elena
authors: E
authors: Bossi
authors: Department of Biotechnology and Life Sciences, University of Insubria, Varese, Italy.
authors: Raffaella
authors: R
authors: Cinquetti
authors: Department of Surgical and Morphological Sciences, University of Insubria, Varese, Italy and.
authors: Marcella
authors: M
authors: Reguzzoni
authors: Department of Surgical and Morphological Sciences, University of Insubria, Varese, Italy and.
authors: Andrea
authors: 0000-0002-9423-5446
authors: A
authors: Moriondo
mesh_terms: D000818:Animals; D001552:Benzazepines / Q000494:pharmacology; D002317:Cardiovascular Agents / Q000494:pharmacology; D002586:Cesium / Q000494:pharmacology; D002712:Chlorides / Q000494:pharmacology; D003964:Diaphragm; D005260:Female; D064428:Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D007150:Immunohistochemistry; D000077550:Ivabradine; D042601:Lymphatic Vessels / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D015221:Potassium Channels / Q000235:genetics / Q000378:metabolism; D011743:Pyrimidines / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D060888:Real-Time Polymerase Chain Reaction; D014661:Vasoconstriction
chemical_list: D001552:Benzazepines; D002317:Cardiovascular Agents; D002712:Chlorides; C513835:HCN3 protein, rat; C513836:HCN4 protein, rat; C578667:Hcn1 protein, rat; C578712:Hcn2 protein, rat; D064428:Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels; D015221:Potassium Channels; D011743:Pyrimidines; C082246:ICI D2788; D002586:Cesium; D000077550:Ivabradine; C028019:cesium chloride
keywords: lymphatic contractility; lymphatic contraction frequency; lymphatic muscle cells