Ashendel CL

Chijiwa T

Curry WJ

I. Fairweather

J. G. McGeown

Kamemoto ES

Lippe C

M. K. Graham

Samii SI

Sangster NC

Stone DB

Webb RA.

Spontaneous phasic contractions recorded from isolated body strips of Fasciola hepatica were increased in frequency and amplitude by GYIRFamide, an FMRFamide-related peptide (FaRP). Superfusion with guanosine 5′-O-(2-thiodiphosphate) (100 μM, n = 5) reduced the effects of GYIRFamide on both frequency (by 82%) and amplitude (by 75%). The adenylate cyclase inhibitor MDL-12330A (25 μM) increased spontaneous activity. MDL-12330A completely inhibited the frequency response to GYIRFamide and reduced the amplitude response by 66% as measured relative to this elevated basal activity ( n = 6). Inhibition of phospholipase C (PLC) with neomycin sulfate (1 mM) had no direct effect on activity but reduced the frequency response to GYIRFamide by 64% and the amplitude increase by 95% ( n = 9). The protein kinase C (PKC) inhibitor chelerythrine chloride (10 μM) also reduced frequency and amplitude responses by 98 and 99%, respectively, without affecting basal contractility ( n = 5). Phorbol 12-myristate 13-acetate, an activator of PKC, increased contraction frequency and amplitude ( n = 6). It was concluded that GYIRFamide stimulates mechanical activity in F. hepatica through a G protein, via a PLC- and PKC-dependent second messenger pathway.</jats:p

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AJP Regulatory Integrative and Comparative Physiology

Second messengers mediating mechanical responses to the F<scp>a</scp>RP GYIRFamide in the fluke<i>Fasciola hepatica</i>

Second messengers mediating mechanical responses to the F
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Second messengers mediating mechanical responses to the F a

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