TLDR Cromakalim relaxes various blood vessels, while minoxidil sulphate is more selective; they likely act on different potassium channels.
The study compared the effects of two potassium channel openers, cromakalim and minoxidil sulphate, on vascular smooth muscle. Cromakalim uniformly relaxed a variety of different blood vessel preparations, while the actions of minoxidil sulphate appeared more selective. The study suggests that cromakalim and minoxidil sulphate act via different potassium channels and that subtypes of ATP-sensitive potassium channels may account for differences in their properties.
86 citations,
July 1990 in “British Journal of Pharmacology” Diazoxide, minoxidil sulphate, and cromakalim relax rat blood vessels by opening K+ channels, with some differences in their actions.
47 citations,
October 1989 in “Circulation Research” The study explains how minoxidil sulfate causes vasodilation in rabbits by opening potassium channels and inhibiting calcium channels.
90 citations,
January 1989 in “PubMed” 
48 citations,
June 1988 in “PubMed” Minoxidil sulfate relaxes muscle by increasing potassium flow, making it a unique muscle relaxer.
47 citations,
November 1982 in “Journal of Cardiovascular Pharmacology” Nitrendipine and nifedipine effectively block muscle contractions, while papaverine relaxes them and minoxidil needs high amounts to work.
33 citations,
May 1991 in “British Journal of Pharmacology” Cromakalim relaxes various blood vessels, while minoxidil sulphate is more selective; they likely act on different potassium channels.
86 citations,
July 1990 in “British Journal of Pharmacology” Diazoxide, minoxidil sulphate, and cromakalim relax rat blood vessels by opening K+ channels, with some differences in their actions.
