Abstract--1. Testes of Heliothis virescens synthesized ecdystel the optimum calcium titer for testis sheaths stimulated to synl the optimum for testes stimulated in vitro with the peptide 2. Verapamil at concentrations

-1. Testes of Heliothis virescens synthesized ecdystel the optimum calcium titer for testis sheaths stimulated to synl the optimum for testes stimulated in vitro with the peptide 2. Verapamil at concentrations lower than 10 -3 M induced more efficient synthesis when calcium influx was inhibited. 3. Hemolymph of H. virescens was 7 mM in calcium, wh calcium. I N T R O D U C T I O N in oil Gelm dcium ions are involved in vertebrate processes as Terse as regulation of muscle contraction, secretion early synth hormones, digestive enzymes and neurotransbrain tters, transport of salt and water across the gut, d glycogen metabolism in the liver (Rasmussen, iotrol 83). Although not as much evidence has been synth cumulated for insect systems, similar functions for types t 2+ have been indicated (Berridge and Lipke, 1979). optirr of thi :ogenous Ca 2+ are required for response to eclosion rmone by Manduca sexta nerve cord (Truman, types 80) and stimulation of the metabolism of lipid and calciu rbohydrate by fat body exposed to adipokinetic 1978) calci~ rmone and trehalagon (Steele, 1980). Stimulation ' esize ecdysteroid de novo whel extracts containing the pept pin (TE) (Loeb et al., 1987, 191 'nthesis of immunodetectable eccl 3 of testes from H. virescens ~timal in low titers of exogenous s dependence was explored b3 of testes to a range of Ca 2+ til calcium influx antagonist (Rosenbe ), and calcium ionophore A231~ ium transport across membr he neuropeptide neuroaires influx of calcium migratoria (Lange et al., MATERIALS AND METH 3f diuretic hormone in Experimental animals and organs ited by activation and H. virescens were obtained as pupa~ mnels (Maddrell, 1980). Insects Laboratory, Phoenix, AZ, and al ~uca sexta, cultured with adults. Eggs were collected and the re,, 9racicotropic reared and staged as described (Loeb quantities of ecdysone Testes were dissected from H. virescem he external calcium coninstar (digging stage, days 3 and 4) wll he Ca 2+ flux is increased detectable quantities of eedysteroid only TE and after testis fusion (buried stage, c 87, although basal profith and Gilbert, 1986). pupation, when testes secrete ecdystero (1988a,b) reported little addition of TE (Loeb et al., 1984, 1987 ia or calcium channel lesis of juvenile hormone Standard Ringer was 173mM in s~ 9m Locusta migratoria, calcium, 3.7raM in potassium, 180m~ uced by the ionophore, 2.8 mM in bicarbonate. Calcium-free Ri ," synthesis and release, by substituting sucrose (Sigma) (3.61 lesize several ecdysteroid osmotic properties. Analysis by flame al., 1982; Shimizu et al., troscopy indicated the actual Ca 2+ col ecdysone (20HE) is the cium-free Ringer was 4.6 + 0.88/~M. Ho, ue secreted by testes of Ringer plus 10 -4 M EDTA was render~ t Woods, 1989), Lymancalcium according to computer aided cal 1988). Ringer containing other Ca 2+ titer 8) and Ostrinia nubilalis was prepared with sucrose-substituted • • , r i , • , m l l