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Effects of Sperm‐Activating Peptide I on Hemicentrotus pulcherrimus Spermatozoa in High Potassium Sea Water
Author(s) -
Harumi Tatsuo,
Hoshino Katsuaki,
Suzuki Norio
Publication year - 1992
Publication title -
development, growth and differentiation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.864
H-Index - 66
eISSN - 1440-169X
pISSN - 0012-1592
DOI - 10.1111/j.1440-169x.1992.tb00005.x
Subject(s) - hemicentrotus , ibmx , sperm , chemistry , sea urchin , seawater , sperm motility , motility , biology , medicine , endocrinology , botany , microbiology and biotechnology , ecology , stimulation , forskolin
The effects of sperm‐activating peptide I (SAP‐I: Gly‐Phe‐Asp‐Leu‐Asn‐Gly‐Gly‐Gly‐Val‐Gly) on Hemicentrotus pulcherrimus spermatozoa in high [K + ] sea water were examined. In high [K + ] sea water, the respiration rates and motility of H. pulcherrimus spermatozoa were lower than those in normal sea water. SAP‐I did not stimulate the lowered respiration rate or motility, although the peptide bound to the spermatozoa as it does in normal sea water. SAP‐I elevated the sperm cGMP level in 100 mM K + sea water (from 0.37 to 4.81 pmol/mg wet weight spermatozoa) more than those in normal sea water (from 0.21 to 0.93 pmol/mg wet weight). A phosphodiesterase inhibitor, 3‐isobutyl‐1‐methylxanthine (IBMX) and SAP‐I synergistically elevated the cGMP level from 0.35 to 33.08 pmol/mg wet weight in 100 mM K + sea water. However, in high [K + ] sea water, SAP‐I did not increase the cAMP level even in the presence of IBMX. SAP‐I caused rapid, transient elevation of the intracellular pH and Ca 2+ concentration of spermatozoa in normal sea water but not in 100mM K + sea water. SAP‐I did not decrease the apparent molecular weight of sperm guanylate cyclase from 131,000 to 128,000 in high [K + ] sea water. These results suggest that the SAP‐I‐induced elevation of the cGMP level in sea urchin spermatozoa occurs before or independently of membrane hyperpolarization induced by the opening of K + channels.