To test whether hyperkalemia suppresses ventricular fibrillation (VF) by reducing the slope of the action potential duration (APD) restitution relation, we determined the effects of the extracellular K(+) concentration (K(+)](o)) (KCl] = 2.7-12 mM) on the restitution of APD and maximum upstroke velo...

We have shown previously that verapamil reduces the slope of the action potential duration (APD) restitution relation, suppresses APD alternans and converts ventricular fibrillation (VF) into a periodic rhythm. To determine whether these effects result primarily from reduction of the APD restitution...

Ventricular arrhythmias and the proclivity for sudden death have been identified in German shepherd dogs. This disorder is inherited, and affected animals can be consistently produced from an established colony. The arrhythmias are most prevalent in young dogs between 22 and 26 weeks of age, with de...

A perspective on systems containing many action potential waves that, individually, are prone to spiral wave breakup is proposed. The perspective is based on two quantities, 'predator' and 'prey,' which we define as the fraction of the system in the excited state and in the excitable but unexcited s...

Background: Hypothesis: Animals: Methods: Results: Conclusions and Clinical Importance: Lidocaine is most frequently used to treat ventricular arrhythmias. However, lidocaine may have an antiarrhythmic effect for certain supraventricular arrhythmias.We hypothesized that lidocaine would be effective ...

Objectives: Background: Methods: Results: Conclusion: The age-dependence of the development of ventricular arrhythmias was studied in German shepherd dogs with inherited ventricular arrhythmias and sudden death.A colony of German shepherd dogs has been established that exhibit inherited ventricular ...

The relationships between key features of the cardiac electrical activity, such as electrical restitution, discordant alternans, wavebreak, and reentry, and the onset of ventricular tachyarrhythmias have been characterized extensively under the condition of constant rapid pacing. However, it is unli...

1. The transient outward potassium current (Ito) is reduced in canine epicardial myocytes during the acute stage of infection with Trypanosoma cruzi (Chagas' disease). Sympathetic nerve terminals are also destroyed during the acute stage of this disease. To test whether the reduction of Ito is relat...

A novel degradative route to pregnanes has been elucidated in the marine sponge Araphimedon compressa. 22-Dehydrosterols, common in the diet of sponges, are the precursors to pregnanes and apparently are degraded by a mechanism analogous to the dealkylation of phytosterols to cholesterol.

Cyclobutenbriarein A (2), a novel class of C20-rearranged diterpene briarane possessing an unprecedented tricyclo[8.4.0.0(3,6)]tetradec-4-ene ring system was isolated, along with five new briarane diterpenoids (1 and 3-6), from the organic extracts of the Bahamian gorgonian Briareum asbestinum. The ...

The pseudopterosins are a family of diterpene glycosides isolated from the gorgonian coral Pseudopterogorgia elisabethae. These metabolites exhibit potent anti-inflammatory activity, and this review describes our efforts to elucidate their biosynthetic origin. A radioactivity-guided isolation was us...

The pseudopterosins are diterpene glycosides isolated from the marine gorgonian, Pseudopterogorgia elisabethae, which exhibit anti-inflammatory and analgesic activity greater than the industry standard, indomethacin. Previously, we isolated the pseudopterosin diterpene cyclase product, elisabethatri...

OBJECTIVE. To determine the effects of continuous passive motion (CPM) and immobilization on synovitis and cartilage degradation in an experimental model of chronic inflammatory, antigen-induced arthritis. METHODS. After bilateral arthritis induction of knee joints in 22 NZW rabbits, one knee was im...

The triterpene precursor of saponins in sea cucumbers has been identified as parkeol [lanost-9(11)-en-3 beta-ol] [1]. Dissection of the sea cucumbers Holothuria floridea and Actinopyga agassize after incubations with radiolabeled parkeol demonstrated that saponin biosynthesis occurs exclusively in t...

Two new sterols, epipolasterol and 22(23)-dihydroepipolasterol, have been isolated from the marine sponge Epipolasis sp. These are unusual metabolites as they both contain a t-butyl group in the sterol side chain. In addition, the presence of two degrees of unsaturation in the side chain of epipolas...

Isochrysis galbana, one of the most widely used marine microalgae in the rearing of finfish and shellfish larvae, is mass cultured frequently in outdoor tanks. Under prolonged and repeated culture, severe contamination occurs. Axenic isolation of I. galbana from such cultures was best achieved by us...

A biosynthetic study has been performed to elucidate the precise mechanisms of sterol side chain dealkylation in marine sponges. This process resembles that of insects by involving the oxidation of common dietary sterols with unsaturation at C-24(28) (24-methylenecholesterol (8), fucosterol (3), and...