Cardiac gap junctions and gap junction-associated vesicles: ultrastructural comparison of in situ negative staining with conventional positive staining.

Cardiac gap junctions and gap junction-associated vesicles: ultrastructural comparison of in situ negative staining with conventional positive staining.

By comparing in situ negative staining of mammalian heart muscle using La(NO3)3 with conventional positive staining by uranium and lead salts, we showed that 1) the membrane area of rat cardiac gap junctions (GJs) at the intercalated disks is threefold to fourfold greater than previously thought; 2) connexon arrays of cardiac GJ are subdivided into microdomains by connexon-free aisles; 3) profi...

Dako Omnis Dynamic Gap Staining

In vitro formation of gap junction vesicles

A method is described that uses trypsin digestion combined with collagenase-hyaluronidase which produces a population of gap junction vesicles. The hexagonal lattice of subunits ("connexons") comprising the gapjunctions appears unaltered by various structural criteria and by buoyant density measurements. The gap junction vesciles are closed by either a single or a double profile of nonjunctiona...

Ultrastructural changes in gap junctions associated with CO2 uncoupling in frog atrial fibres.

The correlation between gap junction morphology and the state of electrical coupling was investigated in the frog auricle, which presents an atypical gap-junction organization. Electrical uncoupling of the tissue was achieved by perfusion with CO2-saturated Ringer medium. The tissue was fixed with glutaraldehyde and freeze-fractured before and during the application of CO2-saturated Ringer medi...

Magnesium gating of cardiac gap junction channels.

We aimed to study kinetics of modulation by intracellular Mg(2+) of cardiac gap junction (Mg(2+) gate). Paired myocytes of guinea-pig ventricle were superfused with solutions containing various concentrations of Mg(2+). In order to rapidly apply Mg(2+) to one aspect of the gap junction, the non-junctional membrane of one of the pair was perforated at nearly the connecting site by pulses of nitr...