Identification and regulation of the gastric H⁺/K⁺‐ATPase in the rat heart

Abstract

The gastric isoform of H+/K+-ATPase is expressed in rat cardiac myocytes, both at transcript and protein levels. Functional studies indicate that the enzyme could contribute to potassium and pHi regulation in cardiomyocytes.

Negative Inotropy of the Gastric Proton Pump Inhibitor Pantoprazole in Myocardium From Humans and Rabbits

“…Recently, it has been suggested that H ϩ /K ϩ -ATPase may contribute to pH homeostasis in rat myocardium. 7 We therefore investigated the hypothesis that cellular acidosis subsequent to proton pump inhibition might explain the negative inotropy of PPIs. However, our measurements with the H ϩ -sensitive fluorescence dye BCECF did not reveal any significant influence of pantoprazole on pH i .…”

“…In myocardium from rats, the expression of H ϩ /K ϩ -ATPase has been demonstrated at the transcriptional and protein levels. 7 Biochemical evidence and physiological evidence for a myocardial H ϩ /K ϩ -ATPase have also been found. 8 Furthermore, Beisvag and coworkers 7 showed a contribution from the H ϩ /K ϩ -ATPase of Ϸ25% of total 86 Rb ϩ uptake in rat hearts and suggested that the enzyme could contribute significantly to the regulation of myocardial K ϩ and H ϩ homeostasis.…”

“…7 Biochemical evidence and physiological evidence for a myocardial H ϩ /K ϩ -ATPase have also been found. 8 Furthermore, Beisvag and coworkers 7 showed a contribution from the H ϩ /K ϩ -ATPase of Ϸ25% of total 86 Rb ϩ uptake in rat hearts and suggested that the enzyme could contribute significantly to the regulation of myocardial K ϩ and H ϩ homeostasis. Inhibition of H ϩ /K ϩ -ATPase might therefore induce cellular acidosis, which is known to depress myocardial contractility mainly at the level of myofilament responsiveness to [Ca] i .…”

Identification of the β-subunit for nongastric H-K-ATPase in rat anterior prostate

“…Some other subunits have a very strict tissue specificity: ␣ 4 , only in male germ cells; ␤ m , only in striated muscle; ␣ g and ␤ g , primarily in parietal cells of stomach mucosa [there are also reports on detection of gastric H-KATPase subunits in kidney (3) (conflicting with Ref. 11), epididymis (4), inner ear and choroid plexus (36), and heart (7,47)]. The ␤ 3 is expressed in many tissues at relatively low levels, being somewhat more abundant in lung, testis, adrenal, brain, and colon (5,8,24,47).…”

Chronic Pantoprazole Administration and Ischemia–Reperfusion Arrhythmias In Vivo in Rats—Antiarrhythmic or Arrhythmogenic?

“…Both animal and human tissue studies have shown that PPIs have electrophysiological effects, [23] potentially by increasing intracellular calcium concentrations [4]. Calcium concentration is an important factor in myocytes automaticity and focal arrhythmias are usually secondary to increased automaticity.…”