Dextran sulfate activates contact system and mediates arterial hypotension via B2 kinin receptors

To define some of the mechanisms underlying dextran sulfate (DXS)-induced hypotension, we investigated the effects of either the plasma kallikrein inhibitor des-Pro2-[Arg15] aprotinin (BAY x 4620) or the specific bradykinin B2-receptor antagonist Hoe-140 on the hypotensive response to DXS. In the first study, anesthetized miniature pigs were given DXS alone, DXS plus BAY x 4620 in various doses, or saline. As expected, DXS alone produced a profound but transient systemic arterial hypotension with a concomitant reduction in kininogen. Circulating kinin levels, complement fragment des-Arg-C3a, and fibrin monomer were all increased. Treatment with BAY x 4620 produced a dose-dependent attenuation of these effects with complete blockade of the hypotension as well as the observed biochemical changes at the highest dose (360 mg). In a second study, two groups of pigs were given either DXS alone or DXS plus Hoe-140. DXS-induced hypotension was completely blocked by Hoe-140 pretreatment; however, kininogen was again depleted. We conclude, therefore, that DXS-induced hypotension is produced by activation of plasma kallikrein that results in the production of bradykinin and that liberation of bradykinin and its action on B2 receptors in the vasculature are both necessary and sufficient to produce the observed effects on circulatory pressure

Larval Duration, Settlement, and Larval Growth Rates of the Endangered Tidewater Goby (Eucyclogobius newberryi) and the Arrow Goby (Clevelandia ios) (Pisces, Teleostei)

The early life history of the federally endangered tidewater goby (Eucyclogobius newberryi) and its sister species the arrow goby (Clevelandia ios) has been poorly documented to date. Both are endemic to estuarine habitats throughout the California coast, however, habitat use differs between these two species. The arrow goby is commonly found in fully marine tidal bays and mudflats. The tidewater goby, however, prefers lagoons with some degree of seasonal isolation from the sea. Here, we used otoliths to examine the larval duration, size at settlement, and growth rates of newly settled gobies collected from 18 estuaries in California. The tidewater goby had a larval duration that was ~2 days shorter than the arrow goby (23.95 vs. 26.11 days, respectively), but a larger size at settlement based on back-calculated size (12.38 vs. 10.00 mm SL) due to a faster larval growth rate (2.86 vs. 2.60 μm/day-1). There are several reasons that could explain these differences in larval traits, such as differences in temperature or food resources between the two estuary types, or the faster, annual life cycle of the tidewater goby relative to the arrow goby