while we're talking about coffee . . .

[radlick at SIENA.EDU]

For all of you who are wondering about the diuretic effect experienced
when one drinks coffee, caffeine is the culprit.  It belongs to a group of
substances called methylxanthines:  caffeine, theophylline (used to relax
smooth muscles in the bronchi of asthmatics), and theobromine (an
ingredient in chocolate.    

Methylxanthines appear to increase glomerular filtration rate and renal
blood flow.  Hence,  the diuretic effect.  However, a related drug,
aminophylline inhibits reabsorption of solutes (e.g. Na+, Cl-, and K+)
along the proximal tubule.  Thus, more fluid is excreted.

I've just finished my first cup of coffee, so excuse me . . . 

Lynn Radlick
 

Lynn Radlick				Phone/voice mail:  518-783-4185
Biology Department			E-mail:  radlick at siena.edu 
Siena College
Loudonville, New York 12211