Which effect is NOT associated with β blockers?

Beta blockers primarily function by blocking the action of catecholamines, particularly at β-adrenergic receptors. Their effects on the cardiovascular system include decreased heart rate, reduced contractility, and decreased conduction velocity through the atrioventricular (AV) node. This cumulative action leads to a lowering of blood pressure and decreased myocardial oxygen demand.

Regarding aqueous humor, beta blockers like timolol are used in the treatment of glaucoma as they decrease aqueous humor production, thus lowering intraocular pressure.

Furthermore, beta blockers inhibit the secretion of renin from the juxtaglomerular cells of the kidney, which contributes to their ability to lower blood pressure, as renin is a key enzyme in the renin-angiotensin-aldosterone system that regulates blood pressure and fluid balance.

In this context, the effect of increased heart rate is not associated with beta blockers. Instead, beta blockers typically lead to a decrease in heart rate due to their action on β1-adrenergic receptors in the heart. Thus, stating that beta blockers increase heart rate contradicts their known pharmacological effects.