Guillermo J. Pérez

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Small arteries exhibit tone, a partially contracted state that is an important determinant of blood pressure. In arterial smooth muscle cells, intracellular calcium paradoxically controls both contraction and relaxation. The mechanisms by which calcium can differentially regulate diverse physiological responses within a single cell remain unresolved.(More)
Local calcium transients ('Ca2+ sparks') are thought to be elementary Ca2+ signals in heart, skeletal and smooth muscle cells. Ca2+ sparks result from the opening of a single, or the coordinated opening of many, tightly clustered ryanodine receptor (RyR) channels in the sarcoplasmic reticulum (SR). In arterial smooth muscle, Ca2+ sparks appear to be(More)
The goal of the present study was to test the hypothesis that local Ca(2+) release events (Ca(2+) sparks) deliver high local Ca(2+) concentration to activate nearby Ca(2+)-sensitive K(+) (BK) channels in the cell membrane of arterial smooth muscle cells. Ca(2+) sparks and BK channels were examined in isolated myocytes from rat cerebral arteries with laser(More)
The relationship between Ca2+ release ("Ca2+ sparks") through ryanodine-sensitive Ca2+ release channels in the sarcoplasmic reticulum and KCa channels was examined in smooth muscle cells from rat cerebral arteries. Whole cell potassium currents at physiological membrane potentials (-40 mV) and intracellular Ca2+ were measured simultaneously, using the(More)
The role of Ca(2+)-activated potassium (KCa) channels in the regulation of membrane potential, intracellular free calcium ([Ca2+]i) and contraction was investigated in uterine smooth muscle and myometrial cells. In an immortalized human myometrial cell line, oxytocin increased [Ca2+]i and [3H]inositol phosphate formation. Relaxin attenuated the(More)
Ranolazine is a novel antianginal agent capable of producing anti-ischemic effects at plasma concentrations of 2 to 6 microM without a significant reduction of heart rate or blood pressure. This review summarizes the electrophysiologic properties of ranolazine. Ranolazine significantly blocks I(Kr) (IC(50) = 12 microM), late I(Na), late I(Ca), peak I(Ca),(More)
OBJECTIVES The purpose of our study was to detect and characterize potassium channels in the plasma membrane of smooth muscle cells from human myometrium. STUDY DESIGN Plasma membrane vesicles were incorporated into lipid bilayers to record single potassium channel activity. RESULTS We predominantly found a "maxi" calcium-activated potassium channel(More)
BACKGROUND The Brugada syndrome displays an autosomal dominant mode of transmission with low penetrance. Despite equal genetic transmission of the disease, the clinical phenotype is 8 to 10 times more prevalent in males than in females. The basis for this intriguing sex-related distinction is unknown. The present study tests the hypothesis that the(More)
Uterine excitability depends on ion channel activity, the expression of which is regulated by sexual hormones. We show now that the action of protein kinase A (PKA) on large-conductance calcium-activated K+ (KCa) channel activity also depends on the hormonal status. PKA-dependent phosphorylation of reconstituted KCa channels from midpregnant rats usually(More)
BACKGROUND Identification of infants at risk for sudden arrhythmic death remains one of the leading challenges of modern medicine. We present a family in which a common polymorphism (single nucleotide polymorphism) inherited from the father, combined with a stop codon mutation inherited from the mother (both asymptomatic), led to 2 cases of sudden infant(More)