jachymski [ proc. amer. math. soc., 136 (2008), 1359-1373] gave modified version of a banach fixed point theorem on a metric space endowed with a graph. in the present paper, (g, φ)-graphic contractions have been de ned by using a comparison function and studied the existence of fixed points. also, hardy-rogers g-contraction have been introduced and some fixed point theorems have been proved. s...

Dystonia is a disorder of involuntary sustained muscle contraction, which usually affects a focal region of the body but may be generalized and results in twisting contorted movements or abnormal postures. Several clinical subtypes of dystonia have been delineated and many have a strong inherited basis. In this issue of Neuron, de Carvalho Aguiar and colleagues report the identification of miss...

The present study was undertaken to evaluate the role of Na(+)/K(+) pump dysfunction in the development of diabetic neuropathy (DN). Nerve excitability techniques, which provide information about membrane potential and axonal ion channel function, were undertaken in 15 patients with established DN and in 10 patients with diabetes who had no evidence of neuropathy (DWN). Excitability parameters ...

Little is known about how small variations in ionic currents and Ca²⁺ and Na⁺ diffusion coefficients impact action potential and Ca²⁺ dynamics in rabbit ventricular myocytes. We applied sensitivity analysis to quantify the sensitivity of Shannon et al. model (Biophys. J., 2004) to 5%-10% changes in currents conductance, channels distribution, and ion diffusion in rabbit ventricular cells. We fo...

Na(+) homeostasis is a key regulator of cardiac excitation and contraction. The cardiac voltage-gated Na(+) channel, NaV1.5, critically controls cell excitability, and altered channel gating has been implicated in both inherited and acquired arrhythmias. Ca(2) (+)/calmodulin-dependent protein kinase II (CaMKII), a serine/threonine kinase important in cardiac physiology and disease, phosphorylat...

We compared sodium-calcium (Na-Ca) exchange in vascular smooth muscle between spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats. Aortic rings of 11 SHR and 11 WKY rats aged 11-12 weeks were superfused with physiological saline, and isometric tension was measured. Systolic blood pressure was higher in SHR (174 +/- 12 mm Hg) than in WKY rats (132 +/- 4 mm Hg): 1) In the presence o...

BLAUSTEIN, MORDECAI P. Sodium ions, calcium ions, blood pressure regulation, and hypertension: a reassessment and a hypothesis. Am. J. Physiol. 232(3): Cl65C173, 1977 or Am. J. Physiol: Cell Physiol. l(3): C1654173, 1977. -An attempt is made to elucidate the cellular mechanisms which may account for the well-documented correlation between sodium metabolism and peripheral vascular resistance. As...