Effect of vasopressin on intracellular Na+ concentration in cortical collecting duct.

Vasopressin stimulates transepithelial Na+ absorption in the rabbit cortical collection duct (CCD), however, this increase is short-lived and is followed by sustained inhibition of Na+ absorption. Previous studies suggest that increased basolateral Ca2+ influx via a Na+/Ca2+ exchanger may be involved in feedback inhibition of Na+ absorption, accounting for this transient stimulation. The present studies used the Na+ sensitive dye, SBFI, to measure intracellular NA+ ([Na+]i) in the CCD to determine whether either vasopressin or 3'5'cAMP increase cell Na+ in the CCD, thereby increasing Na+/Ca2+ exchange.

Evidence that separate PGE2 receptors modulate water and sodium transport in rabbit cortical collecting duct.

Prostaglandin E2 (PGE2) modulates both water and sodium transport in the rabbit cortical collecting duct (CCD). To determine whether these effects are mediated by separate PGE2 receptors, we compared the effects of PGE2 and its analogue sulprostone in the isolated perfused rabbit CCD. PGE2 increased basal water permeability (hydraulic conductivity), whereas sulprostone did not.

Muscarinic receptor activation inhibits AVP-induced water flow in rabbit cortical collecting ducts.

We examined the effect of carbachol, an acetylcholine analogue, on hydraulic conductivity (Lp) response to 10 microU/ml arginine vasopressin (AVP) in rabbit cortical collecting duct (CCD). In CCDs in which water flow had been established with AVP, subsequent addition of carbachol caused Lp (X10(-7) cm.atm-1.

Monoclonal antibodies that cross-react with the E1 glycoprotein of different alphavirus serogroups: characterization including passive protection in vivo.

A panel of four monoclonal antibodies (mAb) were produced that cross-react with representatives of two different togavirus serogroups, namely sindbis (SIN) and Semliki Forest (SF) viruses, by ELISA and ADCMC assays. Three of these mAb, IgG2a and IgG2b isotypes, passively protected C3H/Hej mice against 10 and 100 LD50 of SF challenge and one, IgM, did not protect against either challenge dose, or even at 1 LD50. All these mAb were cross-reactive with the E1 glycoprotein of the viruses by immunoblotting in which three different patterns of reactivity were evident, suggesting that three epitopes were involved.