Sodium nitroprusside potentiates hydrogen-sulfide-induced contractions in body wall muscle from a marine worm.

Hydrogen sulfide (H2S) at concentrations of about 0.05 to 1 mmol.l(-1) appears to function as a gasotransmitter in vertebrates, analogous to nitric oxide (NO) and carbon monoxide, but the actions of H2S in invertebrate tissue have not been well studied.

Enzymatic hydrogen sulfide production in marine invertebrate tissues.

At least some mammalian tissues produce H2S in vitro from L-cysteine at rates sufficient to have physiological effects. To determine whether tissues of macrofaunal invertebrates have the same capacity, we measured H2S production in tissue homogenates of the Manila clam Tapes philippinarum and the lugworm Arenicola marina. Tissue homogenates from both animals produced significant quantities of H2S gas upon addition of L-cysteine and the enzyme cofactor pyridoxal-5PRIME;-phosphate (10 mmol l(-1) and 2 mmol l(-1), respectively), while only tissues from T.

Morphological adaptations of the respiratory hindgut of a marine echiuran worm.

The echiuran worm Urechis caupo lives in U-shaped burrows in marine mudflats where levels of toxic hydrogen sulfide increase and water becomes hypoxic during low tide. Even in this low oxygen and high sulfide environment, the animal is capable of maintaining aerobic respiration. Gas exchange occures across both the body wall and hindgut.