Compounds of the formula ##STR1## where T is ##STR2## and R(A), R(B), R(C), R(D), R(E), R(F), x and y have the meanings indicated in the claims, and their pharmaceutically acceptable salts are effective inhibitors of the cellular sodium-proton antiporter (Na.sup.+ /H.sup.+ exchanger). These compounds are therefore outstandingly suitable for treatment of all illnesses which are to be attributed to increased Na.sup.+ /H.sup.+ exchange.

Substituted benzoylguanidines, process for their preparation, their use as a pharmaceutical or diagnostic, and pharmaceutical containing them. Described are benzoylguanidines of the formula I ##STR1## where R(1) to R(3) are H, Hal, (cyclo)alkyl, N.sub.3, CN or OH, alkyloxy, phenyl, phenoxy or benzoyl, and their pharmacologically acceptable salts, but with the exception of the compounds benzoylguanidine, 4-chlorobenzoylguanidine, 3,4-dichlorobenzoylguanidine and 3- or 4-methylbenzoylguanidine. They are obtained by reacting a compound II ##STR2## with guanidine, L being a leaving group.

Substituted thiophenylalkenylcarboxylic acid guanidides, processes for their preparation, their use as a medicament or diagnostic, and a medicament containing them. There are described substituted thiophenylalkenylcarboxylic acid guanidides of the formula I ##STR1## in which R(1) to R(5) have the meanings given in the claims, which are outstandingly active antiarrhythmic pharmaceuticals having a cardioprotective component and are outstandingly suitable for infarct prophylaxis and infarct treatment and also for the treatment of angina pectoris, where they also inhibit or greatly reduce the pathophysiological processes in the formation of ischemically induced damage, in particular in the initiation of ischemically induced cardiac arrhythmias, in a preventive manner.

Indenoylguanidines of formula I and formula II, the process for their preparation, their use as medicaments, medicaments containing them, their use as diagnostic agents and medicaments containing them are described. Compounds I are useful for treating cardiac arrhythmias. Further they are useful as cardioprotective agents in mammals, which comprises administering the compound of formula-I or II with the above properties in combination with pharmaceutically accepted carrier to said mammal. ##STR1##

Diacyl-substituted guanidines of the formula I ##STR1## are described where X(1) and X(2) are ##STR2## as defined herein. The compounds are suitable for use as antiarrhythmic pharmaceuticals possessing a cardioprotective component for the prophylaxis and treatment of infarction and for the treatment of angina pectoris, in connection with which they also inhibit or strongly reduce, in a preventitive manner the pathophysiological processes associated with the genesis of ischemically induced damage, in particular associated with the elicitation of ischemically induced cardiac arrhythmias.