High-Salt Intake Augments the Activity of the RhoA/ROCK Pathway and Reduces Intracellular Calcium in Arteries From Rats.
BACKGROUND
We investigated the influence of salt overconsumption on the functionality of the RhoA/Rho-associated kinase (ROCK) pathway and calcium regulation in arteries.


METHODS
The aorta and small mesenteric arteries from rats fed a chow containing 2%, 4%, or 8% NaCl were evaluated in organ baths for the activity of the RhoA/ROCK pathway and intracellular calcium mobilization. Components of these pathways and intracellular calcium levels were also assessed in samples from 4% NaCl group.


RESULTS
In arteries from animals fed regular chow, the ROCK inhibitor Y-27632 reduced the responses to phenylephrine, even when the smallest concentrations (1 and 3 μM) were tested. However, only higher concentrations of Y-27632 (10 and 50 μM) reduced phenylephrine-induced contraction in vessels from high-salt groups. Immunoblotting revealed augmented phosphorylation of the myosin phosphatase targeting subunit 1 and increased amounts of RhoA in the membrane fraction of aorta homogenates from the 4% NaCl group. Under calcium-free solution, vessels from NaCl groups presented reduced contractile responses to phenylephrine and caffeine, compared with the regular chow group. Moreover, decreased intracellular calcium at rest and after stimulation with ATP were found in aortic smooth muscle cells from 4% NaCl-fed rats, which also showed diminished levels of SERCA2 and SERCA3, but not of IP3 and ryanodine receptors, or STIM1 and Orai1 proteins.


CONCLUSIONS
Arteries from rats subjected to high-salt intake are unable to properly regulate intracellular calcium levels and present augmented activity of the calcium sensitization pathway RhoA/ROCK. These changes may precede the development of vascular diseases induced by high-salt intake.
Department of Pharmacology, Universidade Federal do Paraná, Curitiba, Paraná, Brazil.
Sandra
S
Crestani
Department of Physiology, Augusta University, Augusta, Georgia, USA.
Robert Clinton
RC
Webb
Laboratory of Cardiovascular Biology, Department of Pharmacology, Universidade Federal de Santa Catarina, Florianópolis, Santa Catarina, Brazil.
José Eduardo
JE
da Silva-Santos
D000577:Amides / Q000494:pharmacology; D000818:Animals; D001011:Aorta / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D053496:Inositol 1,4,5-Trisphosphate Receptors / Q000187:drug effects / Q000378:metabolism; D008297:Male; D008638:Mesenteric Arteries / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D032389:Myocytes, Smooth Muscle / Q000187:drug effects* / Q000378:metabolism; D000071740:ORAI1 Protein / Q000187:drug effects / Q000378:metabolism; D010656:Phenylephrine / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects; D054645:Protein Phosphatase 1 / Q000187:drug effects / Q000378:metabolism; D011725:Pyridines / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D019837:Ryanodine Receptor Calcium Release Channel / Q000187:drug effects / Q000378:metabolism; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases / Q000187:drug effects / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D017673:Sodium Chloride, Dietary / Q000494:pharmacology*; D000071737:Stromal Interaction Molecule 1 / Q000187:drug effects / Q000378:metabolism; D014661:Vasoconstriction / Q000187:drug effects*; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D020741:rho GTP-Binding Proteins / Q000187:drug effects* / Q000378:metabolism; D054460:rho-Associated Kinases / Q000187:drug effects* / Q000378:metabolism
D000577:Amides; C506948:Atp2a2 protein, rat; C506951:Atp2a3 protein, rat; D004791:Enzyme Inhibitors; D053496:Inositol 1,4,5-Trisphosphate Receptors; D000071740:ORAI1 Protein; C532493:Orai1 protein, rat; D011725:Pyridines; D019837:Ryanodine Receptor Calcium Release Channel; D017673:Sodium Chloride, Dietary; C518857:Stim1 protein, rat; D000071737:Stromal Interaction Molecule 1; D014662:Vasoconstrictor Agents; C108830:Y 27632; D010656:Phenylephrine; D054460:rho-Associated Kinases; C499850:Ppp1r12a protein, rat; D054645:Protein Phosphatase 1; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; C000621224:RhoA protein, rat; D020741:rho GTP-Binding Proteins; D002118:Calcium
blood pressure; calcium sensitization; calcium signaling; high-salt; hypertension; vascular dysfunction; vascular smooth muscle cell.