|Title||Differential glycogen utilization in shark acid- and base-regulatory gill cells|
|Publication Type||Journal Article|
|Year of Publication||2019|
|Authors||Roa J.N, Tresguerres M|
|Type of Article||Article|
|Keywords||acidosis; alkaline tide; Alkalosis; ATPase; energy; exercise; glycogen; Life Sciences & Biomedicine - Other Topics; localization; metabolism; Muscle; pH regulation; soluble adenylyl-cyclase; spiny dogfish; Translocation; Triakis semifasciata; triakis-semifasciata; v-h+-atpase; vacuolar proton-atpase|
Na+/K+-ATPase (NKA)- and vacuolar H+-ATPase (VHA)-rich cells in shark gills secrete excess acid and base, respectively, to seawater to maintain blood acid-base homeostasis. Both cell types are rich in mitochondria, indicating high ATP demand; however, their metabolic fuel is unknown. Here, we report that NKA- and VHA-rich cells have large glycogen stores. Glycogen abundance in NKA-rich cells was lower in starved sharks compared with 24 h post-fed sharks, reflecting higher energy demand for acid secretion during normal activity and glycogen replenishment during the post-feeding period. Conversely, glycogen abundance in VHA-rich cells was high in starved sharks and it became depleted post-feeding. Furthermore, inactive cells with cytoplasmic VHA had large glycogen stores and active cells with basolateral VHA had depleted glycogen stores. These results indicate that glycogen is a main energy source in both NKA-and VHA-rich cells, and point to differential energy use associated with net acid and net base secretion, respectively.