The invention relates to compounds of formula (I) in which the symbols have the meanings given in the claims. Said compounds are inhibitors of the sodium-dependent bicarbonate/chloride ion exchanger which can be used as medicines for the prophylaxis or treatment of a wide range of diseases, for example the treatment and/or prophylaxis of myocardial infarction, angina pectoris, diseases caused by ischaemia, impaired respiration, cardiac ischaemia, ischaemia of the peripheral and central nervous system and stroke, ischaemia of the peripheral organs and limbs and diseases in which cell proliferation is a primary or secondary cause, in the treatment of shock, during surgical interventions and organ transplants or for preserving and storing transplants to be used in surgical interventions. ##STR1##