Role of p21-activated kinases in cardiovascular development and function

p21-activated kinases (Paks) are a group of six serine/threonine kinases (Pak1-6) that are involved in a variety of biological processes. Recently, Paks, more specifically Pak1, -2, and -4, have been shown to play important roles in cardiovascular development and function in a range of model organisms including zebrafish and mice. These functions include proper morphogenesis and conductance of the heart, cardiac contractility, and development and integrity of the vasculature. The mechanisms underlying these effects are not fully known, but they likely differ among the various Pak isoforms and include both kinase-dependent and -independent functions. In this review, we discuss aspects of Pak function relevant to cardiovascular biology as well as potential therapeutic implications of small-molecule Pak inhibitors in cardiovascular disease.     

Intracellular phosphate release by the Na+-K+-activated membrane ATPase

Zusammenfassung An menschlichen Erythrocyten hemmt Phloretin den passiven Austritt von anorganischem Phosphat. Mit Hilfe dieser Wirkung konnte gezeigt werden, dass die Na⁺-K⁺-aktivierte ATPase anorganisches Phosphat nicht direkt nach aussen befördert, sondern im Innern der Zelle freisetzt.     

On the origin of the Mg++-activated ATPase of muscle mitochondrial preparations

Riassunto Nelle preparazioni mitocondriali di muscolo è presente una notevole attività ATPasica stimolata dal Mg⁺⁺, anche se i mitocondri sono intatti e ben fosforilanti. Questa attività ATPasica, stimolata da Mg⁺⁺, appare essere inibita dall'aggiunta di Ca⁺⁺. Poichè questo comportamento è tipico della attività ATPasica associata ai microsomi, gli autori concludono che l'attività ATPasica stimolata da Mg⁺⁺ delle preparazioni mitocondriali di muscolo è molto probabilmente espressione di un inquinamento delle preparazioni stesse da parte di frammenti originanti dal reticolo sarcoplasmico.     

Zn(II)-activated acid phosphatase in liver and metanephros of developing chick

Résumé Pendant le développement embryonnaire du poulet, une phosphatase acide activée au Zinc(II) est présente dans le foie et le métanéphros, mais non dans le cerveau et le cur. L'élévation maximum du taux de cet enzyme se produit dans le foie et dans le métanéphros à des stades différents. Son développement semble être en rapport avec le développement fonctionnel des organes concernés.     

Reversal by lecithin of the amobarbital-induced inhibition of microsomal (Na+K)-activated ATPase

Résumé L'amobarbital de soude inhibe l'activité du (Na+K)-ATPase du réticule sarcoplasmique isolé. Cette inhibition peut être évitée par l'addition de lécithine purifiée. La lécithine pré-incubée en présence de l'amobarbital inhibe (Na+K)-ATPase.     

Postnatal decline of (Ca2+ + Mg2+)-activated membrane ATPase in cattle red cells.

Acitivity of membrane bound (Ca2+ + Mg2+)-stimulated ATPase, associated with Ca2+ outward transport, in calf red cells is high at birth and declines with a rate constant of 0.041 d-1 after the 3rd week. The decline parallels the disappearance of fetal hemoglobin.     

The effect of temperature on Ca2+ uptake and Ca2+-activated ATP hydrolysis by cardiac sarcoplasmic reticulum

Zusammenfassung Der Ca²⁺-Transport und die Ca²⁺-aktivierte ATP Hydrolyse (ATP extra Spaltung) durch Membranen des cardialen sarkoplasmatischen Retikulums zeigen die gleiche Temperaturabhängigkeit. Die Aktivierungsenergie der Ca²⁺-Aufnahme und der ATP extra Spaltung, gemessen bei Anwesenheit von Oxalat, beträgt 16.65±0.87 und 17.93±0.49 Kcal/Mol^–1.     

The effect of temperature on the ouabain-sensitivity of Na+−K+-activated ATPase and fluid secretion by the Malpighian tubules ofLocusta

Summary Temperature markedly affected the ouabain-sensitivity of both the Na⁺–K⁺-activated ATPase activity and the secretion of fluid by the Malpighian tubules ofLocusta. Varying the K⁺ concentration in the bathing medium did not affect the ouabain-sensitivity of the fluid secretory process.     

GPR39: a Zn<Superscript>2+</Superscript>-activated G protein-coupled receptor that regulates pancreatic,gastrointestinal and neuronal functions

GPR39 is a vertebrate G protein-coupled receptor related to the ghrelin/neurotensin receptor subfamily. The receptor is expressed in a range of tissues including the pancreas, gut/gastrointestinal tract, liver, kidney and in some regions of the brain. GPR39 was initially thought to be the cognitive receptor for the peptide hormone, obestatin. However, subsequent in vitro studies have failed to demonstrate binding of this peptide to the receptor. Zn²⁺ has been shown to be a potent stimulator of GPR39 activity via the Gα_q, Gα_12/13 and Gα_s pathways. The potency and specificity of Zn²⁺ in activating GPR39 suggest it to be a physiologically important agonist. GPR39 is now emerging as an important transducer of autocrine and paracrine Zn²⁺ signals, impacting upon cellular processes such as insulin secretion, gastric emptying, neurotransmission and epithelial repair. This review focuses on the molecular, structural and biological properties of GPR39 and its various physiological functions.