Assessment of airway hyperresponsiveness in murine tracheal rings.

Isolated tracheal rings have often been used to directly measure the contractile output of airway smooth muscle (ASM). Here, we describe the method for excising murine tracheas, mounting tracheal rings in organ baths, and measuring the isometric forces generated by the ASM when stimulated by drug additions or electric field stimulation. The apparatus for the setup and the pathways responsible for stimulation are detailed.

In vitro measurements of tracheal constriction using mice.

Transgenic and knockout mice have been powerful tools for the investigation of the physiology and pathophysiology of airways(1,2). In vitro tensometry of isolated tracheal preparations has proven to be a useful assay of airway smooth muscle (ASM) contractile response in genetically modified mice. These in vitro tracheal preparations are relatively simple, provide a robust response, and retain both functional cholinergic nerve endings and muscle responses, even after long incubations.

BK channel β1 subunits regulate airway contraction secondary to M2 muscarinic acetylcholine receptor mediated depolarization.

The large conductance calcium- and voltage-activated potassium channel (BK channel) and its smooth muscle-specific β1 subunit regulate excitation–contraction coupling in many types of smooth muscle cells. However, the relative contribution of BK channels to control of M2- or M3-muscarinic acetylcholine receptor mediated airway smooth muscle contraction is poorly understood. Previously, we showed that knockout of the BK channel β1 subunit enhances cholinergic-evoked trachea contractions.

BK channel beta1-subunit regulation of calcium handling and constriction in tracheal smooth muscle.

The large-conductance, Ca2+-activated K+ (BK) channels are regulators of voltage-dependent Ca2+ entry in many cell types. The BK channel accessory beta1-subunit promotes channel activation in smooth muscle and is required for proper tone in the vasculature and bladder. However, although BK channels have also been implicated in airway smooth muscle function, their regulation by the beta1-subunit has not been investigated.

The influence of long-term Aloe vera ingestion on age-related disease in male Fischer 344 rats.

The effects of long-term Aloe vera ingestion on age-related diseases were investigated using male specific pathogen-free (SPF) Fischer 344 rats. Experimental animals were divided into four groups: Group A, the control rats fed a semi-synthetic diet without Aloe vera; Group B, rats fed a diet containing 1% freeze-dried Aloe vera filet; Group C, rats fed a diet containing 1% charcoal-processed, freeze-dried Aloe vera filet; and Group D, rats fed the control diet and given whole leaf charcoal-processed Aloe vera (0.02%) in the drinking water.

Assessing effects of long-term food restriction on myocardial energetics in the isolated heart preparation.

Food restriction (FR) may increase longevity by increasing the efficiency of energy utilization by some organs. We tested whether any effect of FR on the energy efficiency of isolated, isovolumically beating hearts could be observed, by studying four groups of rats: (1). AL fed (AL) 10-13-month-old rats, (2).