{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T17:48:56Z","timestamp":1760204936839},"reference-count":0,"publisher":"American Physiological Society","issue":"6","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Journal of Neurophysiology"],"published-print":{"date-parts":[[1993,12,1]]},"abstract":"<jats:p> 1. Zinc-protoporphyrin-IX (ZnPP-IX) is an inhibitor of the enzyme heme-oxygenase-2 (HO-2) and consequently has been used to examine the role of carbon monoxide production in neural tissues. We have measured voltage-gated Ca current in AtT-20 pituitary cells using the whole-cell patch-clamp technique and have assessed the effects of extracellularly applied ZnPP-IX and related compounds. 2. Ca currents evoked by depolarizing steps from a holding potential of -90 mV were of the high-threshold, slowly inactivating type. Fifty-six percent of this current was blocked by 10 microM nifedipine and 16% by 3 microM omega-conotoxin with the remainder resistant to both drugs in combination, suggesting that the total Ca current was a mixture of L, N, and possibly P-type conductances. 3. Bath application of ZnPP-IX resulted in an irreversible, dose-dependent attenuation of Ca current. Five micromolar ZnPP-IX produced a 62% reduction of peak current amplitude with no shift in the current-voltage relation, 0.5 microM produced a 19% reduction, and 0.05 microM produced a variable response, either a small transient attenuation or potentiation. 4. The attenuation of Ca current by 5 microM ZnPP-IX could be nearly completely blocked by co-application of superoxide dismutase in the bath (90 U\/ml) but not by addition of an inhibitor of cGMP-dependent protein kinase to the internal saline (KT5823, 1 microM). 5. Other inhibitors of heme-oxygenase with similar potency such as tin-protoporphyrin-IX (Sn-PP-IX) and Zn-deuteroporphyrin-bis-glycol (ZnBG) did not attenuate Ca current when applied at 5microM.(ABSTRACT TRUNCATED AT 400 WORDS) <\/jats:p>","DOI":"10.1152\/jn.1993.70.6.2673","type":"journal-article","created":{"date-parts":[[2017,12,24]],"date-time":"2017-12-24T23:07:05Z","timestamp":1514156825000},"page":"2673-2677","source":"Crossref","is-referenced-by-count":30,"title":["Protoporphyrins modulate voltage-gated Ca current in AtT-20 pituitary cells"],"prefix":"10.1152","volume":"70","author":[{"given":"D. J.","family":"Linden","sequence":"first","affiliation":[{"name":"Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205."}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"K.","family":"Narasimhan","sequence":"additional","affiliation":[{"name":"Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205."}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"D.","family":"Gurfel","sequence":"additional","affiliation":[{"name":"Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205."}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"24","container-title":["Journal of Neurophysiology"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.physiology.org\/doi\/pdf\/10.1152\/jn.1993.70.6.2673","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2019,9,9]],"date-time":"2019-09-09T01:18:04Z","timestamp":1567991884000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.physiology.org\/doi\/10.1152\/jn.1993.70.6.2673"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[1993,12,1]]},"references-count":0,"journal-issue":{"issue":"6","published-print":{"date-parts":[[1993,12,1]]}},"alternative-id":["10.1152\/jn.1993.70.6.2673"],"URL":"https:\/\/doi.org\/10.1152\/jn.1993.70.6.2673","relation":{},"ISSN":["0022-3077","1522-1598"],"issn-type":[{"value":"0022-3077","type":"print"},{"value":"1522-1598","type":"electronic"}],"subject":[],"published":{"date-parts":[[1993,12,1]]}}}