Transient expression of a ventricular myosin heavy chain isoform in developing chicken intrafusal muscle fibers.

Sections of chicken tibialis anterior and extensor digitorium longus muscles were incubated with monoclonal antibodies against myosin heavy chains (MHC). Ventricular myosin was present in developing secondary intrafusal myotubes when they were first recognized at embryonic days (E) 13-14, and in developing extrafusal fibers prior to that date. The reaction in intrafusal fibers began to fade at E17, and in 2-week-old postnatal and older muscles the isoform was no longer recognized.

The role of the sympathetic nervous system in hypertension.

The sympathetic nervous system plays an important role in the regulation of arterial pressure, and increased sympathetic nervous system activity has been implicated as a primary precursor of hypertension in both humans and animal models of the disease. To date, the mechanism that potentiates the increase in sympathetic nervous system activity has not been fully elucidated. Imbalances in several neurotransmitters and neuromodulators are present during the development of hypertension, and these directly and indirectly contribute to increased release of noradrenaline onto the postsynaptic targets of the sympathetic nerves.