[Physician - Pharmacist Communication about Potentially Severe Drug Interactions].

Introduction: Potentially serious drug interactions are often detected by pharmacists. In such cases fast communication with the General Practitioner (GP) is required. However, contacting physicians by telephone is often difficult.

Overexpression of junctin causes adaptive changes in cardiac myocyte Ca(2+) signaling.

In cardiac muscle, junctin forms a quaternary protein complex with the ryanodine receptor (RyR), calsequestrin, and triadin 1 at the luminal face of the junctional sarcoplasmic reticulum (jSR). By binding directly the RyR and calsequestrin, junctin may mediate the Ca(2+)-dependent regulatory interactions between both proteins. To gain more insight into the underlying mechanisms of impaired contractile relaxation in transgenic mice with cardiac-specific overexpression of junctin (TG), we studied cellular Ca(2+) handling in these mice.

Enhanced cardiac function in mice overexpressing protein phosphatase Inhibitor-2.

Objective: Protein phosphatase 1 (PP1) has been implicated in the control of cardiac function. Cardiac specific overexpression of the catalytic subunit, PP1c, results in hypertrophy and depressed contractility.

Methods: To further address the role of PP1, transgenic mice (TG) were generated that overexpress in heart a functional COOH-terminally truncated form (amino acids 1-140) of the PP1 inhibitor-2 (I-2(140)).

Overexpression of the catalytic subunit of protein phosphatase 2A impairs cardiac function.

Reversible protein phosphorylation is an essential regulatory mechanism in many cellular functions. In contrast to protein kinases, the role and regulation of protein phosphatases has remained ambiguous. To address this issue, we generated transgenic mice that overexpress the catalytic subunit alpha of protein phosphatase 2A (PP2A) (PP2Acalpha) in the heart driven by the alpha-myosin heavy chain promoter.

Altered signal transduction in cardiac ventricle overexpressing A(1)-adenosine receptors.

Objective: The aim of the present study was to assess the effects of A(1)-adenosine receptor (A1-AR) stimulation in ventricle of A(1)-adenosine receptor overexpressing mice (transgenic mice, TG).

Methods: Effects of the A(1)-adenosine receptor agonist R-PIA ((-)-N(6)-phenylisopropyladenosine) on phosphorylation of phospholamban (PLB), Ca(2+) transients, Ca(2+) currents and cell shortening were studied in isolated ventricular cardiomyocytes.

Results: R-PIA alone did not affect contractility in isolated electrically stimulated cardiomyocytes from wild-type mice (WT) or TG.

Impaired relaxation in transgenic mice overexpressing junctin.

Objective: Junctin is a major transmembrane protein in cardiac junctional sarcoplasmic reticulum, which forms a quaternary complex with the ryanodine receptor (Ca(2+) release channel), triadin, and calsequestrin.

Methods: To better understand the role of junctin in excitation-contraction coupling in the heart, we generated transgenic mice with targeted overexpression of junctin to mouse heart, using the alpha-MHC promoter to drive protein expression.

Results: The protein was overexpressed 10-fold in mouse ventricles and overexpression was accompanied by cardiac hypertrophy (19%).