Inhibition of the late sodium current slows t-tubule disruption during the progression of hypertensive heart disease in the rat

Am J Physiol Heart Circ Physiol. 2013 Oct 1;305(7):H1068-79. doi: 10.1152/ajpheart.00401.2013. Epub 2013 Jul 19.

Abstract

The treatment of heart failure (HF) is challenging and morbidity and mortality are high. The goal of this study was to determine if inhibition of the late Na(+) current with ranolazine during early hypertensive heart disease might slow or stop disease progression. Spontaneously hypertensive rats (aged 7 mo) were subjected to echocardiographic study and then fed either control chow (CON) or chow containing 0.5% ranolazine (RAN) for 3 mo. Animals were then restudied, and each heart was removed for measurements of t-tubule organization and Ca(2+) transients using confocal microscopy of the intact heart. RAN halted left ventricular hypertrophy as determined from both echocardiographic and cell dimension (length but not width) measurements. RAN reduced the number of myocytes with t-tubule disruption and the proportion of myocytes with defects in intracellular Ca(2+) cycling. RAN also prevented the slowing of the rate of restitution of Ca(2+) release and the increased vulnerability to rate-induced Ca(2+) alternans. Differences between CON- and RAN-treated animals were not a result of different expression levels of voltage-dependent Ca(2+) channel 1.2, sarco(endo)plasmic reticulum Ca(2+)-ATPase 2a, ryanodine receptor type 2, Na(+)/Ca(2+) exchanger-1, or voltage-gated Na(+) channel 1.5. Furthermore, myocytes with defective Ca(2+) transients in CON rats showed improved Ca(2+) cycling immediately upon acute exposure to RAN. Increased late Na(+) current likely plays a role in the progression of cardiac hypertrophy, a key pathological step in the development of HF. Early, chronic inhibition of this current slows both hypertrophy and development of ultrastructural and physiological defects associated with the progression to HF.

Keywords: calcium handling; heart failure; late INa; ranolazine; t-tubule.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetanilides / pharmacology*
  • Animals
  • Calcium Channels, L-Type / drug effects
  • Calcium Channels, L-Type / metabolism
  • Calcium Signaling / drug effects*
  • Disease Models, Animal
  • Disease Progression
  • Dose-Response Relationship, Drug
  • Heart Failure / etiology
  • Heart Failure / metabolism
  • Heart Failure / physiopathology
  • Heart Failure / prevention & control
  • Hypertension / complications
  • Hypertension / diagnostic imaging
  • Hypertension / drug therapy*
  • Hypertension / metabolism
  • Hypertension / physiopathology
  • Hypertrophy, Left Ventricular / etiology
  • Hypertrophy, Left Ventricular / metabolism
  • Hypertrophy, Left Ventricular / physiopathology
  • Hypertrophy, Left Ventricular / prevention & control
  • Male
  • Myocytes, Cardiac / drug effects*
  • Myocytes, Cardiac / metabolism
  • NAV1.5 Voltage-Gated Sodium Channel / drug effects
  • NAV1.5 Voltage-Gated Sodium Channel / metabolism
  • Piperazines / pharmacology*
  • Ranolazine
  • Rats
  • Rats, Inbred SHR
  • Ryanodine Receptor Calcium Release Channel / drug effects
  • Ryanodine Receptor Calcium Release Channel / metabolism
  • Sarcoplasmic Reticulum Calcium-Transporting ATPases / metabolism
  • Sodium / metabolism*
  • Sodium Channel Blockers / pharmacology*
  • Sodium Channels / drug effects*
  • Sodium Channels / metabolism
  • Sodium-Calcium Exchanger / drug effects
  • Sodium-Calcium Exchanger / metabolism
  • Time Factors
  • Ultrasonography

Substances

  • Acetanilides
  • Atp2a2 protein, rat
  • Calcium Channels, L-Type
  • L-type calcium channel alpha(1C)
  • NAV1.5 Voltage-Gated Sodium Channel
  • Piperazines
  • Ryanodine Receptor Calcium Release Channel
  • Scn5a protein, rat
  • Sodium Channel Blockers
  • Sodium Channels
  • Sodium-Calcium Exchanger
  • sodium-calcium exchanger 1
  • Sodium
  • Ranolazine
  • Sarcoplasmic Reticulum Calcium-Transporting ATPases