Heat acclimation and heat stress have different effects on cholinergic muscarinic receptors.

In this brief report we have proved that membranal changes take place upon short-term heat acclimation. These changes may switch on a cascade of transient acclimatory compensatory responses as well as long-term processes. The changes observed in the MR profile are heat acclimation specific, and differ from those observed upon heat stress. These bring about functional changes in the signal transduction pathway for water secretion in the submaxillary salivary gland. A recovery period from heat stress, similar to STHA, leads to MR upregulation and decreased binding affinity. This response, however, is more pronounced than that observed upon STHA. The functional importance of the phenomenon is unclear. However, it could designate a novel component of the heat shock response.