Molecular characterisation and functional interrogation of a local natriuretic peptide system in rodent pituitaries, alphaT3-1 and LbetaT2 gonadotroph cells.

In the pituitary, C-type natriuretic peptide (CNP) has been implicated as a gonadotroph-specific factor, yet expression of the CNP gene (Nppc) and CNP activity in gonadotrophs is poorly defined. Here, we examine the molecular expression and putative function of a local gonadotroph natriuretic peptide system. Nppc, along with all three natriuretic peptide receptors (Npr1, Npr2 and Npr3), was expressed in both alphaT3-1 and LbetaT2 cells and primary mouse pituitary tissue, yet the genes for atrial-(ANP) and B-type natriuretic peptides (Nppa and Nppb) were much less abundant.

Impact of physiological variables and genetic background on myocardial frequency-resistivity relations in the intact beating murine heart.

Conductance measurements for generation of an instantaneous left ventricular (LV) volume signal in the mouse are limited, because the volume signal is a combination of blood and LV muscle, and only the blood signal is desired. We have developed a conductance system that operates at two simultaneous frequencies to identify and remove the myocardial contribution to the instantaneous volume signal. This system is based on the observation that myocardial resistivity varies with frequency, whereas blood resistivity does not.

Enhanced left ventricular systolic function early in type 2 diabetic mice: clinical implications.

It is unclear whether the increase in availability of substrates for energy production in diabetes can lead to enhanced systolic function early in the disease, before the onset of structural changes to the myocardium. To examine this issue, BKS.Cg-m +/+ Lepr db (db/db) mice with type 2 diabetes and wild type controls had left ventricular pressure-volume relationships determined in situ.

Enhancement of contractility with sustained afterload in the intact murine heart: blunting of length-dependent activation.

Background: It has been hypothesized that because of its rapid heart rate, the intact murine heart functions near maximal contractility in the basal state. If this hypothesis is correct, then the fast and slow components of myocardial length-dependent activation should be blunted compared with larger mammals.

Methods And Results: Mice (n=24) were anesthetized, and via an open chest, LV pressure-volume relationships were determined by a dual-frequency conductance catheter system.

HAND1 and HAND2 are expressed in the adult-rodent heart and are modulated during cardiac hypertrophy.

The HAND basic Helix-Loop-Helix (bHLH) transcription factors are essential for normal cardiac and extraembryonic development. Although highly evolutionarily conserved genes, HAND cardiac expression patterns differ across species. Mouse expression of HAND1 and HAND2 was reported absent in the adult heart.