H I rotation curves have been presented and analyzed for 21 bright spirals in the center of the Virgo Cluster. The curves look similar to those of spirals in the field in that the great majority of them are flat or still rising at the Holmberg radius. A detailed comparison with synthetic curves derived from field spirals shows good agreement, if we take into account the fact that the radio data were obtained with much lower angular resolution. Our main conclusion is that the mass distribution in spirals is not affected in an obvious way by their environment. This confirms the results presented by Chincarini and de Souza (1985), based on optical rotation curves. Our sample contains the most hydrogen-deficient spirals in the Virgo Cluster. A few galaxies very close to the cluster center have lost their H I to within almost the turnover point of the rotation curve. In spite of this, the Tully-Fisher relation derived for our sample does not differ significantly from the ones derived from larger samples containing fewer H I-deficient galaxies; thus the relation can probably be used safely for cluster spirals. Two galaxies that have been stripped heavily have profile widths that are significantly smaller than that expected from the Tully-Fisher relation, but even there we could argue that it is their luminosity, and not their width, that is unusual.
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Guhathakurta et al. (1988) studied this question.