These results suggest that the increased "sensitivity" to caffeine of MHS swine muscle fibers is a nonspecific response related, at least in part, to the high resting [Ca2+]i and not an increased caffeine sensitivity of the sarcoplasmic reticulum Ca2+ release channel per se.

Stellate ganglion neurons, important mediators of cardiopulmonary neurotransmission, are surrounded by satellite glial cells (SGCs), which are essential for the function, maintenance, and development of neurons. However, it remains unknown whether SGCs in adult sympathetic ganglia exhibit any functional diversity, and what role this plays in modulating neurotransmission. We performed single‐cell RNA sequencing of mouse stellate ganglia (n = 8 animals), focusing on SGCs (n = 11,595 cells). SGCs were identified by high expression of glial‐specific transcripts, S100b and Fabp7. Microglia and Schwann cells were identified by expression of C1qa/C1qb/C1qc and Ncmap/Drp2, respectively, and excluded from further analysis. Dimensionality reduction and clustering of SGCs revealed six distinct transcriptomic subtypes, one of which was characterized the expression of pro‐inflammatory markers and excluded from further analyses. The transcriptomic profiles and corresponding biochemical pathways of the remaining subtypes were analyzed and compared with published astrocytic transcriptomes. This revealed gradual shifts of developmental and functional pathways across the subtypes, originating from an immature and pluripotent subpopulation into two mature populations of SGCs, characterized by upregulated functional pathways such as cholesterol metabolism. As SGCs aged, these functional pathways were downregulated while genes and pathways associated with cellular stress responses were upregulated. These findings were confirmed and furthered by an unbiased pseudo‐time analysis, which revealed two distinct trajectories involving the five subtypes that were studied. These findings demonstrate that SGCs in mouse stellate ganglia exhibit transcriptomic heterogeneity along maturation or differentiation axes. These subpopulations and their unique biochemical properties suggest dynamic physiological adaptations that modulate neuronal function.

ORFΔcoq2Δ, yeast double mutant harboring a gene deletion in a designated open reading frame plus a deletion in COQ2; pABA, para-aminobenzoic acid; PC, phosphatidylcholine; Pyr12, 1-pyrene dodecanoic acid; SD, synthetic dextrose medium; vCLAMP, vacuole-mitochondria patch; WT, wild-type parental yeast strain; YPD, rich growth medium containing dextrose as a fermentable carbon source; YPG, rich growth medium contain glycerol as the sole non-fermentable carbon source.

No abstract

The cell bodies of postganglionic sympathetic neurons innervating the heart primarily reside in the stellate ganglion (SG), alongside neurons innervating other organs and tissues. Whether cardiac-innervating stellate ganglionic neurons (SGNs) exhibit diversity and distinction from those innervating other tissues is not known. To identify and resolve the transcriptomic profiles of SGNs innervating the heart we leveraged retrograde tracing techniques using adeno-associated virus (AAV) expressing fluorescent proteins (GFP or Td-tomato) with single cell RNA sequencing. We investigated electrophysiologic, morphologic, and physiologic roles for subsets of cardiac-specific neurons and found that three of five adrenergic SGN subtypes innervate the heart. These three subtypes stratify into two subpopulations; high (NA1a) and low (NA1b and NA1c) Npy-expressing cells, exhibit distinct morphological, neurochemical, and electrophysiologic characteristics. In physiologic studies in transgenic mouse models modulating NPY signaling, we identified differential control of cardiac responses by these two subpopulations to high and low-stress states. These findings provide novel insights into the unique properties of neurons responsible for cardiac sympathetic regulation, with implications for novel strategies to target specific neuronal subtypes for sympathetic blockade in cardiac disease.

No abstract

Stellate ganglion neurons, important mediators of cardiopulmonary neurotransmission, are surrounded by satellite glial cells (SGCs), which are essential for the maintenance and development of neurons. However, little is known about the heterogeneity and physiological functions of glia in adult sympathetic ganglia, and their role in modulating neurotransmission. Therefore, we performed single‐cell RNA sequencing of dissociated mouse stellate ganglia (n=8 animals), specifically focusing on the SGCs. SGCs were identified by high expression of glial specific transcripts, S100b and Fabp7 (n = 13370 cells). Microglia and Schwann cells were identified by expression of C1qa/C1qb/C1qc and Ncmap/Drp2, respectively, and excluded from further analysis. Subclustering of the SGCs revealed six distinct transcriptomic profiles. Expression levels of different glial marker genes were compared between these six subgroups to describe and study their distinct molecular profiles. The first subgroup was classified as glia‐progenitors (n = 1689; principle markers: Ng2 and Sox2). Pathway analysis demonstrated activation of pathways involved in self‐renewal of neural precursor cells and maintenance of radial glia cells. The second subgroup was identified as quiescent ‘astrocyte‐like’ glia (n = 3710; principle markers: Id3 and Aldoc). Accordingly, pathway analyses demonstrated active pathways involved in regulation of quantity and morphology of astrocytes. A third cluster (n = 2930) showed many similarities to the second cluster, but had a more reactive transcriptomic profile. Activated pathways included ones that were associated with astrocyte hypertrophy and quantity of reactive astrocytes. Hence, this cluster is referred to as the more active 'astrocyte‐like' cells and characterized by increased expression of the early response markers Mt1 and Klf2. The fourth cluster had a very distinct transcriptomic profile and had high expression levels of genes involved in the inflammatory response (n = 808; principle markers: Ifit3b and Gm4951). Correspondingly, pathways involved in immune response of cells and astrocytosis in the brain were enriched. Therefore, these cells may represent highly activated 'astrocyte‐like' SGCs. The fifth and sixth cluster were characterized by the expression of genes involved in axon development or maintenance and therefore showed more similarities with oligodendrocytes. These clusters were referred to as the 'oligodendrocyte‐like cells' and could be separated in myelinating ‘oligodendrocyte‐like’ cells (n = 1507; markers: Egr2 and Cryab) and non‐myelinating ‘oligodendrocyte‐like’ cells (n = 951; markers: Gap43 and Kcna1). Accordingly, both clusters showed much overlap in their activated pathways, most of which were associated with the cell cycle of oligodendrocytes or Schwann cells. However, pathways associated with cholesterol syntheses were downregulated in the sixth cluster. Our findings indicate transcriptomic heterogeneity within SGCs in mouse stellate ganglia and suggest functional subgro...

The cell bodies of postganglionic sympathetic neurons innervating the heart primarily reside in the stellate ganglion (SG), alongside neurons innervating other organs and tissues. Whether cardiac-innervating stellate ganglionic neurons (SGNs) exhibit diversity and distinction from those innervating other tissues is not known. To identify and resolve the transcriptomic profiles of SGNs innervating the heart we leveraged retrograde tracing techniques using adeno-associated virus (AAV) expressing fluorescent proteins (GFP or Td-tomato) with single cell RNA sequencing. We investigated electrophysiologic, morphologic, and physiologic roles for subsets of cardiac-specific neurons and found that three of five adrenergic SGN subtypes innervate the heart. These three subtypes stratify into two subpopulations; high (NA1a) and low (NA1b and NA1c) neuropeptide-Y (NPY) -expressing cells, exhibit distinct morphological, neurochemical, and electrophysiologic characteristics. In physiologic studies in transgenic mouse models modulating NPY signaling, we identified differential control of cardiac responses by these two subpopulations to high and low stress states. These findings provide novel insights into the unique properties of neurons responsible for cardiac sympathetic regulation, with implications for novel strategies to target specific neuronal subtypes for sympathetic blockade in cardiac disease.